Firstly, a tad amount of history. The Coopers kits you brew come from a family brewery from Adelaide (South Australia) .. same place Rupert Murdoch made his mark on the publishing world .. just thought I'd throw that in .. same company makes some brilliant swill beers that many in the Australian homebrew scene love (Mike Jackson loved the Sparkling Ale, the Pale Ale is good and my favourite bottled beer in the Foreign Extra Stout) .. yet we won't touch the kits. Not because they aint good for a kit (biggest selling kits in world) just that the kits and the commercial swill don't taste the same. Now, that said, you like the Coopers kit, listen to me.
Just about every Aussie home brewer started on Coopers kits. We loved them cos they didn't taste like ordinary Aussie swill beer. Like Nero, we fiddled, like pig farmers we mucked about, like American presidential candidates we debated, we argued and we fought, all about what best to do with Coopers kits.
My answer. The kits are reasonable. Any better, they'd cost you more. Any worse, you couldn't drink the muck. I still believe them the best kit beer easily available. How to make them better ?
Firstly, a crystal malt addition is recommended. Don't get excessive, but Coopers need a little body. Can you mini mash - a little malted wheat addition adds heaps to a Coopers kit (especially head retention and a little flavour / body). You don't need too much extra malt (DME or LME) as Coopers has plenty of flavour. And late hops additions are very welcome. Unless you want a real hoppy brew, late aroma additions are really needed and appreciated.
So without insulting american HBS suppliers, watch out for HBS additions you don't know about. Unless your local HBS bloke has made a Coopers kit with the giznos he's trying to flog you, add your own additions to the kit. Do your research, listen to this advice. Work out HOW you want your brew to TASTE (sorry for screaming) and adjust your additions accordingly. When you want to know what you want you're beer to taste like, then ask your local bloke for help.
Best of luck seppos.