depends how bad it is. you can be mild or get freakin crazy. I use 3M products most of the time.
mild- good rubbing compound followed by polish and wax
moderate- 3M heavy compound, polish, wax
freakin crazy- color sand with 600 grit or higher, polish, wax did it to my first epic. looked brand new when i was done. its ALOT of work but looks awesome.