If you do any sort of online marketing you'll know that one of the keys to success is a regular flow of engaging, entertaining, impactful material.

That might be in blog posts, emails, videos or podcasts. You might focus just on adding value with your content to build credibility and trust with potential clients. Or you might use your stories and examples to make your sales letters or promotions more interesting and effective.

Whatever you do, you need “stuff”. You need to be able to put pen to paper, keyboard to blog, webcam to youtube and to create material that your potential clients are going to find useful, entertaining, thought-provoking, challenging, insightful, funny, valuable, maybe even life-changing.

Doing that regularly is a big ask. If you're anything like me you'll have days where you sit there thinking “what on earth am I going to write about today?”.

So here are some sources of inspiration I've used to come up with ideas and themes for blog posts, emails and other content. At least one of these will work for you every time you're drawing blanks.

1. Revisit your Ideal Client Profiles
As part of the fundamentals of your marketing, you should have drawn up profiles of your ideal clients. If you haven't, watch this video on the most effective way to do it for marketing purposes.

By reviewing your ideal clients' most important goals and aspirations, problems and challenges, and what they need to know and feel about you to be ready to hire you you'll be reminded of the big themes you need to be writing about to grab the attention of your audience and strengthen your credibility with them.

2. Think of a Specific Client
You can go even deeper than your generic client profiles. Think of a specific client (or potential client) of yours. What problems or challenges are they facing right now? Chances are many of your readers will be facing those issues, so write something helpful about those specific topics.

3. Review your recent emails
Check your recent emails from clients, prospects and subscribers. What questions have they been asking? Could any of those questions (and answers) be turned into a blog post or email? Chances are the answer is yes.

4. Draw on your own business experience
Tell stories about some of your own experiences with the challenges your clients are facing. Stories are always interesting to read, they're unique to you, and they'll establish your credibility because they're about how you did something personally, not about theory.

Here's an important tip though: talk about problems you faced and how you overcame them – that helps people empathise with you and see you as someone like them they can learn from. Don't just blather on about all your achievements: that makes you seem like a show-off.

5. Draw on your own personal experience
The stories you share don't have to be about the exact same situations your clients find themselves in. You can draw lessons from personal experience too. One of my most replied to emails ever is about when (prompted in no uncertain terms by Kathy) I had to get off my butt and just knuckle down to clear up our garden and create the vegetable patch I'd wanted for years. A simple lesson that could be applied to business too and resonated with a lot of people.

6. Share stories of your clients' successes
Just like your own stories, client stories are hugely interesting to readers. Again tell the story so they can build a connection, don't just show off about the results. And get permission if you're mentioning names, of course.

7. Reflect on the media and popular culture
Pick up on a story in the news or in the popular culture your clients are likely to know (sitcoms, soaps, books, films, music – whatever they're likely to be tuned into). Extract a lesson from that. But don't just use the same events everyone else is writing about. In Olympic or World Cup years I usually get as far as the 5th blog post or email about how we can learn some lesson from them before it feels passé. By the 37th it's an immediate turn-off.

8. Create new experiences
Go out and do something you can write about that's interesting to your audience. I regularly report on what's working and not working for me in my marketing. And often half the reason for testing some new marketing approach is so that I can report back on how well it works. In the world of comedy, Dave Gorman is a master at doing stuff he can then write or talk about as I explain here.

By the way, did you see what I did there? That Dave Gorman blog post is an example of reflecting on popular culture.

9. Observe the world around you
If you keep your eyes open there's a myriad of things going on around you all the time that you can comment on. A good (or bad) customer service experience at a shop can obviously give you material on customer service if that's what you talk about. But also marketing (how customer service impacts the impression you give in the marketplace), operations (how to build processes for effective customer service), leadership (how great leaders create customer-focused companies), culture (about how to embed a customer service culture), even IT (how great systems free up people to focus on customers) or pretty much anything if you put your mind to it.

The trick is to take notes. Always have a notebook or recording device with you (I use Evernote on my iPhone) and have the discipline to use it whenever anything strikes you as interesting. This is something comedians do all the time – they're forever collecting observations on interesting things they see and working them into jokes and routines later.

10. Capture your thoughts
In tip 9 I asked you to capture your observations of the world on paper or electronically. But you should also do that with any thoughts or ideas that pop into your head. Most of us have at least one or two half-decent ideas every day that could be turned into an email or blog post. But unless we write them down we'll forget them.

11. Relax
I get some of my best ideas for articles when I'm relaxing after thinking about a topic rather than when I'm doing the thinking. It's just the way the brain works. So make sure you do activities that half-engage your brain to allow the ideas to flow out. Cooking, gardening, even taking a shower.

12. Rant
Think about something that really makes you angry and write about it. The words will flow quickly (though they may need a bit of editing afterwards!). Don't turn into someone who just rants and complains all the time though. It's not a very pleasant personality characteristic. But every now and then it's good to get something off your chest – especially if it's something your readers are likely to agree with. It helps make you feel more human too.

13. Challenge accepted wisdom
Think of something you believe or do that goes against the grain of what everyone else thinks or does in your field. It'll make for interesting reading and it'll mark you out as being different. My blog post on Why Networking Doesn't Work (For Me) is a good example.

Don't fake it though. One tactic many people use that just grates is to have a deliberately controversial headline then back down in the article. I remember a video from a few years ago entitled “Social Media Doesn't Work”. Sounded interesting so I watched it (at least the start). The subtitle then came in: “…if you don't do it right”.

Yep, the stunning insight this video offered was that something doesn't work if you don't do it right. And the guy delivered it like he was bringing words of wisdom down from Mount Sinai. Duh. That's a credibility loser, not a credibility builder.

14. Revisit your old thinking
Pretty much every time I read something I wrote over a year or so ago I come up with new ideas on the same topic. My thinking and experience have almost always moved on. In fact sometimes just reading something from a week previously can trigger follow-up thoughts. One of my very first articles for this blog back in 2008, Selling With Stories was followed up a week later with an article on Answering Tough Questions With Stories in this way.

15. Use other people's articles to trigger your own
Sometimes when you read someone else's article you get a whole bunch of your own thoughts. Rather than keeping them to yourself or making a huge comment on the other person's article (that no one will read), turn it into a proper article of your own. Make sure you credit and link to the original source of course.

16. Turn social media discussions into articles
If you're active on social media – especially Linkedin or Facebook groups – you'll probably find you actually contribute a lot of content in discussions. Go back to that content and turn it into something that's going to do you a lot more good in your business: a blog post or an email.

17. Create a “collection”
More suitable for blog posts that emails, but one way you can create a really valuable resource that gets lots of visitors is to collect wisdom from around the web on a particular topic and summarise it with links to the original. I did it with 21 of the Best Resources for Improving Your Website Conversions. Peep Laja does it a lot with articles like 21 Ways You're Screwing Up Your Landing Pages and Pricing Strategies: 13 Articles You Need to Read.

18. Make a case study
Dive in-depth into a real-world example This is always hugely interesting for people and often much more interesting than a list of generic tips or a theoretical example. So for example rather than “5 tips for improving your Facebook Page” do “Case Study: How I improved my Facebook Page and got 123% more website visitors”.

19. Do Q&A
I've done about a dozen video blog posts (for example, this one on Lead Nurturing) by asking my email subscribers what the biggest questions they have about marketing are and creating a resource to help them with the top questions. Not only does this help me create content, it also helps me keep my finger on the pulse of what's important to my clients and subscribers.

20. Set yourself a target
This blog post started off as being a short email to my subscribers with a couple of quick tips. But then I realised I had too many ideas, so I created a blog post with the title “17 Sources of Inspiration for Blog Posts and Emails”. I only had 5 or 6 at the time, but by setting myself a target of 17 I forced my creative juices into play. As it turns out, I've powered on past 17 already and will need to rename the article!

21. Calm down, it's only a blog post
One of the things we do which prevents us from creating emails and blog posts is to get too worried about “hitting the ball out of the park” every time. We absolutely should only be putting valuable material out there, but not everything needs to be a magnum opus (like this post!). Sometimes a short email with a simple story can provide tremendous insight. Sometimes it's enough just to be amusing and entertaining in your emails and to raise a smile: that'll mark you out as being very different to your competitors. We don't have long, worthy discussions with our best friends all the time. Sometimes (often) we just shoot the breeze. But we always (almost) enjoy their company.

So relax a bit. Just put something good out there, not necessarily something perfect.

And please, if you found this helpful tweet it out to your community, and add your ideas on sources of ideas in the comments below.