7. Over-promising, under-delivering
Don't make promises you can't keep. You may feel compelled to agree to unreasonable deadlines, for example. You need to set people's expectations, and this may entail learning to say "no" on occasion or asking for help when you need it. A good rule of thumb is always aim to over-deliver. If you finish a project a few days ahead of schedule, people will appreciate it all the more.