TIPS:
Preparation is everything - The phrase "Oh the judge'll never notice that!" couldn't be more wrong.
Turn the model upside down. - It's amazing to see what you've missed when you do that.
Ensure that the model is eye catching - painting a Spacemarine in Ultramarine Blue and expecting it to stand above the rest may well be a road to disapointment.
"Light is King" J.W.M.Turner - and so it is, and especially for model painters we need to make sure that light and lighting on models works. In our case contrast is our ally.
Basing - Our figures are frozen in position so if you are trying to make the figure tell a story then it needs to be sympathetic to the environment, i.e. A figure in barbarian furs is going to look out of place in a modern office setting, but right in woodland. Also try to keep similar colours in the base as are present in the figures painting but without making it obvious after all you want to show off the figure not drown it out.