I don't often do top 10 lists, but most of this one came to me in a dream (which is a pretty sad admission in itself) and it kind of amused me.

In reverse order:

10. Bad mouthing a client. We all have clients that we dearly love, but who drive us wild. There's a terrible temptation to moan and bitch about them to colleagues, business partners and friends. Don't. Delivered with affection by you, you might get away with it. Repeated second hand you certainly won't.

9. Courting a competitor. It doesn't often happen (but it happened once to me). Sometimes clients can get upset if we approach or start working with one of their competitors – especially if it's a particularly direct or aggressive competitor. Even though you know you won't be sharing anything confidential and you're probably working in a different area, it can raise big concerns. Best to avoid it, or check with your current client first.

8. Being too salesy. Clients don't like being sold to all the time – especially not when they're paying you to be there. Developing client relationships and winning extension work, expansion work and referrals which currently being employed by them is subtle art you have to learn.

7. Making a mistake. We all make mistakes. Clients are usually very forgiving of small mistakes – but sometimes not. Make quality control a priority. Far more serious than making a mistake though, is:

6. Covering up a mistake. You might be able to cover up a mistake and get away with it, or fix it before the client notices. It's surprising how often they find out though. And if they do, they now know that you prioritise your interests above theirs. It's difficult to come back from that.

5. Overpromising. Even if you do a brilliant job, if you've promised the earth and you only give them the moon, they'll be disappointed. And they'll know not to trust your word in future.

4. Surprises. Clients hate being surprised. Even more so if they find out about it from their colleagues, their customers or their bosses rather than you. Make sure you warn them in advance of potential risks, and you keep them regularly informed. Even surprisingly good news can be embarrasing if you're the last to hear about it.

3. Taking key decisions without involving them. Even if clients have hired you because you're the expert not them, it can be a big loss of face for them if you take key decisions without consulting with them and reviewing the options. Agree very early in your engagement how you will take decisions and who will be involved. And stick to it.

2. Not being open. Touch feely stuff this – but important. Any close relationship will go through high points and low points. There'll be moments when the relationship is tested. As your relationship develops, it needs to move beyond the factual and rational into the emotional. But many professionals feel uncomfortable sharing their feelings. If a workshop or meeting or event didn't go as well as planned, instead of being open about their disappointment and how they feel, they put on their “game face”. They hide their feelings and call it professionalism. They never develop really strong relationships with clients because they never let them in.

1. Indifference. This doesn't sound like a big crime – but it's #1 because it's the cause of more broken relationships than anything else. When you've stopped working for a client (or even when you still are but you're really focused on delivery) it's so easy to stop communicating. All those great corridor chats they found so valuable suddenly go away. You don't seem to care any more. The truth is that you still love them, but you're just so darn busy. But to them, it feels like you don't care – and that the only reason you had a relationship with them was because they were paying you at the time.

That's my top 10 – comments on some of the things you've seen that screw up client relationships would be much appreciated – just drop them in the box below.