best bang for the buck is the search function.
there are a few things depending on how mechanically knowledgable you are. if not much, leave it stock and enjoy better gas mileage, a smooth, and comfortable ride. however, if you have the skill and some money, make a 718
(there is a thread on a 550/650 project overbored to 718 i think) also you can drop some weight off it.
but ya, head work, k&n pods, exhaust, the 650 cam, hondamans ignition will get rid of adjusting points.