Make sure you have some chain lube, I like Maxima Chain Wax, but everybody has their own tastes, and put it on when the bikes been warmed up a little.
Get some air filter cleaner spray and filter oil spray. Spray the filter with the cleaner, hose it down, let it dry then spray on the oil. You need to keep that air filter clean.
Buy 6 new spark plugs; put 2 new ones in the motor, keep 2 on the machine, and 2 in your toolbox. I'd say get the BR8EIX Iridium plugs, a little more expensive but burn much hotter and harder to foul in a rich environment.
One of the most important things to do is get a service manual. Easiest place to get it is from your dealer. This will tell you how to adjust the chain (very important), change the oil, and every other little maintenance thing that needs to be done and when. It will also tell you how to do just about anything else to the bike, as your experience and experimentalness grows.
This board is a great place to learn, and I'm sure we'll think of some other things.