They called me and set up an appointment to go to a local Blood Clinic. When you get there, I simply registered that I was giving blood. I sat down and had to answer a few questions about my personal info (name, address, etc). She then pricked my finger to check my iodine levels, Im not sure why. I then had to fill out some paperwork regarding my general health, such as wheather I took drugs by needles, or been exposed to HIV. I then went to a sort of "mini-interview" where they ask some more personal qusetions. Such as have you had gay sex with a man while unprotected, taken cocaine, been exposed to SARS or HIV or a bunch of other diseases.
After this stage, they take you to a type of collapseable couch. They lay you down, stick a needle in your arm, and suck out about a pint of blood (i think). All very simple, the whole process takes about 30 minutes.
I highly push people to give blood. Its such a simple thing to do, and you could potentially be saving lives. The only excuse I've heard, other than you have diseases, is "well, Im afraid of needles". To this I say, a moment's pain is well worth the saving of a life. In Canada, its all donated, you dont get paid for it. But Im sure in America, you get paid for it. So thats an added bonus for all you Americans.