Today I had my very first mammogram. I have a family history of breast cancer (my Mom is a breast cancer survivor! She was diagnosed shockingly early at 40!!) so my OB/GYN thought it a must to start my mammograms on the early side. She explained that having an early mammogram helps the doctors get a baseline so if any problems do arise they have a basis of comparison.
The experience was MUCH less uncomfortable than I expected. If you are not a terribly modest person (which I was before I did IVF and had kids ;D) then you will be fine. The technician was very funny and helpful and put me at my ease. I unrobed from the waist up and took off jewelry. When it was my turn they did an inspection of the skin and marked any moles. Then the tech positioned me for a series of four shots. Two of each breast. One from the top and one from the side. The do smoosh your boobs but unless you are fairly wimpy I can't say that it hurt. It was not fun but it didn't hurt. All in all the appointment took about 20 minutes and was way easier that I anticipated.
I believe that I will now have to have them every two years until I am 40 then I will need to do annual mammos. It was an appointment I was not looking forward to but it was no worse that a trip to the gyno (at least IMO).
So if you're putting it off, don't. It's not that bad!