First of all, what's he looking to brew?
Main things that apply are obviously temp control, sanitation and yeast health. Get him in to good habits from the get go.
People throw a mixed bag when it comes to kits, that there's no way to make a good one, I'm not one of those... I've had some shit kit brews, I've also had some shit all grain brews, but the majority of each have been pretty good.
Some steeped grain, short boils w/hops, dry hop additions. make a difference to your more basic kits.
I only brewed a few myself years ago, the more expensive kits do seem to be a lot tastier but still benefit from a bit of propping up... but you can do the same to coopers.
I hear that the cooper's family secret amber ale is a great drop with no special additions just the kit and malt, even the kit yeast works well with it, evidently.