Working w/ LED's

Before designing or even getting the mice running on their wheel, I figured I'd see if someone could give some advice on using LED's. My intentions are to put LED's in the cupholders, under each side of the dash, & a couple strips under the side panels. What's the best plan of attack? Should I buy pre-assembled lights or buy the parts separately? Also, are any transformers needed or are they as easy as running to a switch? Thanks for anyone's assistance!

these are the LED strips i bought for under the dash and side panels of my boat. you can choose the size you want and they are waterproof (to the best of my knowledge).
http://www.v-leds.com/Interior-LED/G...61954-1-3.html