What to look out for... the first 10 points have to be rust.
Parts prices are silly. Though now the value of a good E30s is going up there's more places stocking bits and even places starting to make some of the NLA bits from BMW.
Enjoy... it'll probably bankrupt you but at least you'll enjoy the process.
BTW... they never made an E30 coupe... only 2 door and 4 door sedans, tourings (station wagon) and convertibles