Before each ride:
- If the chain is dry, put a drop of lube on each link pin (where the links meet). Backpedal the chain for a minute to work the lube into the pins and wipe it down with a rag.
- Squeeze the brakes. If they feel mushy, dial out (that's counterclockwise) the barrel adjusters on the levers or at the brake arms.
Once a month: Check shifting and brakes, lube cables, and wheels. Use lube on suspension the fork sliders.
Every three months: Check brake pads and inspect chain rings and cogs for wear, inspect bolts for proper tightness and grease the seatpost.
Every six months: Overhaul the suspension fork, thoroughly clean the drivetrain and replace the chain twice a year.
Once a year: Give your bike a full wash. Take it to the shop to replace the cables and housing, lube the bearings and replace gritty ones, true the wheels, replace the brake pads and overhaul the fork.
If any of this sounds overwhelming, just bring it by your local bike shop. They'll be more than happy to help.