do not lean back. do not fidget. do not over explian your answers.do not go into an interview without researching the job discription. do not put your legs out. do not cross your legs. sit up strait...
You should dress according to how you see others working there. Stop in before your interview to just look around. Sometimes being over dressed can hurt your chances. Don't be too flashy or exposed....
Either it's anything that you've done in the past that has to do with the job application you're applying for; or it it's stuff that you have trouble/problems/etc with & things that you are good...