Forks- if they aren't leaking leave them alone. Wipe off dust/mud from the stanchions after every ride. If you keep the seals clean they will last forever.
Chain- Lube every few rides- the lube requirement will vary depending on where you ride and what lube you use. Replace chain every 3,000 miles or when it stretches enough to be seen on a chain checker.
Sprockets- Replace every 2-3 chains. sprockets and chains will wear out together. A worn chain will wear out your drivetrain faster, if the chain is replaced on time you will get 6-9,000 miles out of your sprockets.
Suspension- lube as needed when it starts to squeak.
Wheels- take a look before every ride, just eyeball them. If they look relatively straight (less than 1/2'" of movement) leave them alone. If they are tweaked, true them as needed.
If you want to make your drivetrain last don't shift it under load. Other than that just strap on a helmet and enjoy.
