I used to just keep my underwear on (ie knickers!) when I used to use them.
And you can get special creams that you put on to make you tan faster and make the result last longer, if you go to a salon they will normally be able to give you some samples to try.
Two minutes sounds about fine but if you are really pale then they might recommend that you dont use them at all, are you going to a salon? If yes, you will probably have to fill out a questionnaire about your skin type etc so they can evaluate that information and tell you how long you should use it for. If you arent going to a salon, make sure you use the sunbed sparingly and leave it a few days before going on again.