Stormy is right on. I am in no way advocating intentional flight into icing conditions, but most older GA airplanes can carry a fair amount. I know plenty of people who have done so and it's not uncommon. I say this because if you over-react to a little light rime ice and panic, you could turn a common and controllable situation into a disaster.

If you fly in an ice-prone area, make sure you a ready for an inadvertent icing encounter...

1) Know your POH procedures for icing (by memory).
2) Study up on where/when icing occurs in the local airmass. Find out of if severe icing, especially severe clear ice, is likley in your area...this is bad.
3) Ask an experienced local where the icing is likely to be found (they'll know).
4) Have an escape plan based on your airplane, the local terrain, and loacl airmass condition.
5) Check Wx reports (including PIREPs) before and during flight,
6) Stay calm, execute your plan, coordinate with ATC.
7) Monitor the aircraft for performance problems or instrument malfunctions.

If you have to land carrying ice, follow your POH procedures...they will probably tell you to not change the flap setting and to land fast to account for unkown aerodynamic properties of the wing. The more ice, the faster you want to land. Ideally, if you can climb/descend into warmer air or even sunshine, you may be able to melt the ice before landing. This could take a while and would depend on your fuel situation (you will burn fuel faster at an unpredictable rate if carrying ice).