ok I presume you know they are real mags nit just standard five spokes ant way if they are painted there is not really much you need to do. if you get them covered in road salt just rinse them off when you get home. and blob over any chips with a bit of paint
If the paint starts "snaking" badly then get them re-painted ASAP, i found that out when a big corrosion spot appeared on mine, got them re-painted by a bloke in Melton who knows what he is on about and only cost £35 per wheel!!
Just keep an eye on them because they go quickly!!
try a thin layer of vasalene in the winter mate,you cant see it and it makes all the road grime a million times easier to get off when you wash em in hot soapy water!!!
I just keep washed off with soapy water and a quick wipe over with WD 40, like everyone says just keep an eye out for paint flakes & chips. And be wary of "fast" tyre fitting machines.