If you are VERY fair skinned, dont even bother with the tanning beds. I am very much like you seem to be and I will not tan. I went in the tanning bed every other day for a month before I went to Cancun last year and my color didnt change a bit. I just slathered on the sunscreen a few time each day and I was fine. However, if you are going to snorkel or anything, be sure to get environmental safe sunscreen. You can get it at any health food or organic store. Its the same stuff, just doenst kill the coral.
Amazingly, I didnt burn at all the whole week I was out in the sun. Its all about the suncreen!