i have tried to straiten one before with some ok results, still rubbed a bit. ended up buying a new one anyway. after you handle the rotor pick up a can of brake and parts cleaner, clean the rotor before you use it, even new ones. your skin has enough oil to possibly cause problems. more enviromentally friendly way to clean the rotor after you fix it would be alcohol or warm soapy water. the spray can is good to clean the caliper and pads with out disassembly.
most bike shops can give you advice on general upkeep on you bike, lubes, cable tweeks, brake adjustments. if you want to get more into the mechanics of it check out Park Tools, the shop i worked at in Canada offered Park Tool School, great program, started with basics and went as far as complete rebuilds and wheel building. there might be a shop around here that offers that.