Basic maintenance on your own bike is critical to making sure your bike shifts well, brakes well, rides well. The first thing you want to look at is your chain. You always want to keep you chain relatively clean and well oiled. What you want to do is first clean it with some degreaser and then run a rag across it pulling all the grime off it and then conservatively apply chain oil to it. After you've applied chain oil to all of the chain links on the chain, run the gears a little bit. Allow the oil to seep into the chain. After that's done you want to take a clean rag and wipe all the excess oil off the chain. You don't want to have a lot of oil on the chain when you're done with this. You want to have it just in the pins.
Another thing you want to do to make sure your bike is riding properly is that the chain isn't stretched or worn out or the cassette it isn't worn out. Chain get worn out every thousand miles or so. There is a way to checking to stretch of a chain. Chains are very similar to timing belts in cars. Ideally if you race your bike, you'll want to replace your chain and cassette at least once a year, depending on the mileage you put in, you might want to replace the chain and cassette twice a year.
Brakes are another area you want to be conscious of maintaining. Brakes are very simple to adjust. There's a cable running from here up to the brake, it's actually on this side. The cable stretches as it gets worn. The cable can easily be pulled back in with this knob or loosening this bolt and retightening the clamp. What you want to look for in a properly setup brake is just a little bit of pull. You don't want the brake this far out. You also don't want the brake really, really tight, where it's just a little bit of pull. You want about a half of centimeter. The most important thing to remember for maintaining your bike is after it rains, you definitely want to clean the chain. Your going to wipe down the bike, you want to get rid of as much salt and grim from both the crank, the derailleurs, and the chain as much as possible. And that's what you need to know to properly maintain your bike.