Present yourself in the right tone that highlights your star qualities. It is all very well saying you are great at something, but can you support this with real life examples? Don't be arrogant, but be prepared to back up your assertions. A complete 'no no' is to talk down your current previous employer, this only makes you look bitter and reflects negatively on you.
Turn your weaknesses into strengths- Lets face it everyone has weaknesses, so don't pretend that you are exempt from this rule. There is no need to over-do your weaknesses either, simply demonstrate that you have recognised any shortcomings and strive to overcome them.
"My time management skills have been poor in the past, as I always try to be thorough. I have now been delegating tasks and the results have been positive"
"I have found that my organisation skills have improved dramatically since I have been prioritising my workload first thing every morning"
If you lack technical expertise in a particular area, face it head on and admit, "this isn't my strongest area, but I'm sure I can get up to speed rapidly, with hard work and attention"