Generally your skin type is darker the higher the number, so a skin type I is very fair skin. Here's a website to help you determine which one you are:
http://www.spa-medical.com/fitzpatrick_skin_typing_test.htm
As for side effects, if you are concerned about it, you can opt to use Melanotan I instead of Melanotan II. It generally does not produce the sexual sides, and appetite loss associated with Melanotan II. I do believe you have to use a higher dose on the Melanotan I though, so it may cost a bit more to use. Check
www.melanotan.org on the discussion forums for more info, they have forums for both drugs.
Most people start out doing a loading phase, but I've found that if you are not a skin type I or lower end of skin type II that it is probably not necessary and will save you money and prevent sides as well. A lower dose over a longer period of time is best, and gives you a more even all over tan. If you do the loading phase, the parts of your body with the most melanocytes will get darkest faster and can produce uneven results. When I loaded my face got the darkest the fastest and my arms didn't get as dark as quick. Now that I've lowered the dose and been on it a while, everything looks much better and even. Like I said earlier I started out doing 1mg/day for the first week and got extremely dark without tanning. If you do tan, it further stimulates the melanocytes to produce more melanin and speeds the process. I personally would wait a week after using to start tanning to let it build in the system a little, especially if you are fair skinned.
Right now Im using .5mg every other day and I tan between one and three times a week and I look very Latin. LOL After summer, just two shots a week is sufficient for a maintenance dose for a lighter tan for me I'm sure. If I ever have to start over again I will skip the loading phase and just do the .5mg/eod until I reach my desired color.