Whatever you do, don't run your chain unlubricated, which not only will shorten the life of your sprockets and chain but also subjects you the rider to increasing risk of the chain jamming or jumping off the sprockets, which can cause a crash. WD-40, the subject of endless debates as to whether it should be used to clean your chain, definitely should NOT be used to LUBE your chain. WD-40 is a solvent, not a lubricant.

Get yourself a can of spray lube and lightly lube your chain before every ride. Here in China you can get your bike spray washed almost anywhere for 5 or 10 RMB, which will knock all the gunk and crap off the chain. Do that, then pull out your spray lube and hit her again.

cheers