Cover every square inch of the bike in lard. It'll keep it from rusting. If you're vegetarian/vegan, you can use vegetable shortening, but you'll have to reapply more often.

Seriously, though, just wipe it down, make sure the chain is properly lubed, etc. You'll probably get some spot rusting on your fastener heads, where the paint/chrome has been scored by a hex key or screwdriver. If you use a Brooks saddle, rub in a little proofide. Buy some fenders if you plan to ride in the rain frequently.