To get a pre-tan I would go to the tanning bed and start about 3 weeks before you leave so you have a nice base-tan that will prevent you from getting burnt during the trip. Any tanning salon you go to will tell you what will work best for your skin and how long you should be in a bed. I prefer stand-up beds, because I think it's a better tan and you don't have to lie down in something that someone has sweat in even if they do clean them I find it a little unnerving.