I'm on the pill to prevent pregnancy, but I use condoms to prevent STDs. Sometimes I use spermicide, too. I know... overkill? Nah, you can never be too careful. Besides, spermicide can add extra lubrication.
I have used the BCP and after that the sponge, which they took off the market. Then I got pregnant, I tried an IUD and it made me crazy. It made me bleed more and made my cramps worse. I kept it in for about a year I think. Then I begged my doctor to put me out of my misery since it was very dangerous to ever be pregnant again. He tied my tubes when I was 23. I've never regretted it.
Blue, the pill works by tricking the body into thinking it's pregnant, by adding estrogen and/or progesterone which are naturally secreted during pregnancy. The body thinking you are pregnant does not release an egg. Then you take a placebo for 5 days which releases the lining of the uterus. It's actually quite brilliant, and fairly safe. The doses are very low these days as well.