How can I tell whether or not I have skin cancer?

I'm a teen, I am predominantly white with a hint of Native American. I've pretty much always had moles and beauty marks on my face and on my body. But just recently (within the past few months) they're showing up quite frequently! I have several small beauty marks, which are ever so slightly raised, in several locations on my face and body. I've always really thought "Well, if I don't get the family cancer, I'll probably get skin cancer from all this". But I'm getting genuinely scared... I've read some stuff in Seventeen Magazine about skin cancer symptoms, and none of them seem to match my particular situation. But I'm still fairly concerned how can I get more information BEFORE going to a dermatologist? Is there a website I can go to? I tan in the sun, I don't normally wear sunscreen unless my mom's around, I only sunburn in harsh conditions after a long period of time. Please Help! :/