First let me start by saying I wish you all the best on your endeavor! I had started to process of being a surrogate myself last fall - it didn't go well. Here is my story & what I learned form the experience:
I had a very close friend of mine lose a baby in her 2nd trimester & she almost died too. It was very devistating to her & her husband. She was told no more pregnancies. So I offered to be a surrogate since I had a relatively easy time w/ my pregnancies. Once all the legal paperwork & initial testing was complete (it took months) we were finally able to start on the drugs & hormones to see if my body would respond to artificial stimulation. Well, I learned more about my body, my pregnancies, & being a woman in those few months than I had in my life! I found out how strong my hormones are & resistant to drugs they are and that my pregnancies weren't as "easy" as I originally thought. My husband was very supportive through the whole process - make sure you have a good support system! (He was most looking forward to unprotected sex.) I thought I was finally in the clear after being on the pill for 2 months & we had sex. Two days later I went in for my weekly check up & found out I was ovulating & due to timing there was a chance that I might get pregnant! I had to stop everything & wait! I felt awful & guilty & dreaded telling my friend! Fortunately she was very supportive also & totally understood. I got my period & we started the drugs all over again. We (the doctors & I) tried for 3 cycles to get my body to respond properly, each time uping the drug dosages. It was killer. They are basically putting your body into early menopause so you don't ovulate, but then giving you hormones so the lining of you uterus will thicken like it does when you do ovulate.
I eventually had to withdraw because the side effects were too much for me. I had horrible headaches, was short tempered w/ my kids, bruises from the needles, plus all the typical symptoms of menopause! And during the whole pregnancy scare, I was actually excited at the prospect, even though I thought our family was complete! It was the most gut wrenching decision & it broke my heart to have to tell my friend, but I couldn't go on.
I think what you are doing is very noble & having embarked on the adventure myself I know you have only the best of intentions. I did too & will forever have to live with the guilt of letting my friend down, but I don't regret my decision; surrogacy wasn't for me. It takes a strong woman to do it so kudos to you!
My advice: make sure you do lots of research before you sign anything - the web is an invaluable resource. Don't go in blind like me, just believing in faith, make sure you know what you're getting into. I wasn't prepared for all I experienced & never expected for it to get as bad as it did. I too enjoyed being pregnant & had a relatively easy time conceiving so I figured this would be easy too, I was SO wrong! Conceiving naturally vs. artificially is two totally different ballgames! I wish I had known before I started so I could have been more mentally prepared. Read up on the drugs they will be putting you on & the side effects. Know your family's medical history. Be prepared to be poked & prodded like you have never been before! Make sure you are comfortable w/ needles, you will be giving yourself shots everyday (I quickly had to get over my phobia!) Mostly, as I said before, have a good support system in place & Be prepared!!
I wish you the best of luck & hope you have greater success than I did!
PS Feel free to contact me if you want to talk about it further.