The team lead must avoid these attributes of his/her personality:

He/she always have greater understanding of project they should never ask about the project plan or anything which they are supposed to know because this degrade them in eye of other Team members.

This is basic fact that all leading position doesn't matter he is project manager or team lead are very sensitive there are always other people who want to jump on those positions so be always loaded with extra knowledge, skills and discipline.

During lack of right person in team (let's say QA) the team lead should be able to work instead.

Be critical about your performance before somebody else become.