I don't think you can start too young as long as you don't use anything too harsh. I'd go to a larger boots and have a general peruse as you'll get a lot of different prices.
If you think you always look tired, I alwyas feel I always look tired and use this under eye concealor which is like the ysl once but is a number 7 own make and I love it, it's really brightening - also a white eye pencil on the rims of your eyes will brighten.
I have just got a few samples of eye creams of demalogica from beautyflash.co.uk....the eye bright is nice and i love the multi vitamin cream for eyes and lips.
ALso clarins eye contour balm is nice...and it's for people with sensitive skin.
:-)