Start with your primary care provider. Have a whole body mole check and ask advice regarding frequency of exams. Your primary care provider can get you started, and that provider can refer you to dermatology for a more thorough examination. Then, you should have regular exams.
If you notice a mole changing, get it checked out. When in doubt, get it checked out!
I remember reading somewhere that people with loads of moles live longer on average. Don't know where I read that... nor why that could possibly be. But, there it is. If I recall correctly, something like 40 moles is the tipping point.... Interesting, eh? Hmmmm - now I think I need to go figure out where I read that.