I use a lube that also has a solvent in it (many lubes these days do that). Lay a rag on the rear wheel so you don't get lube on the rim, as that will cause your brake to not work. Turn the crank backwards and dribble some lube on the chain until you have done the whole chain. Then hold the crank and scrub the bottom run of the chain back and forth a few times until it's clean. Turn the cranks to get the next section of chain and do it again. Repeat until done. Takes less than a minute. I do it every 100 miles or so. More often when riding in rain.

If your chain still has the sticky grease that comes on most chains it'll pick up a lot of gunk. It may take a couple times of cleaning as described above to get the sticky stuff off. When you install a new chain its better to remove the sticky stuff from the outside of the chain before you put it on. It's a good lube so you don't want to clean it off the inside of the chain, just the outside. Wipe it off with paper towels with a little wd-40 or some other solvent on them.

I use a home brew of 50% synthetic two-stroke oil and 50% mineral spirit, because I have a lot of old two-stroke oil from my road racing days. But any good quality oil would work. Or you can buy boeshield or chain-l or any other wet lube. I've tried "dry" lubes and they don't lubricate very well.

Every so often I remove the cassette and clean it (wd-40 and paper towels). When I remove the chain for maintenance I'll clean off the chainrings.