i had 4 years in permie employment in two seperate jobs. the second was a client of the first company i worked for so kinda already had my work floating around the web offices so i foot in the door!
Now a contractor for 7 months so far.
a) best thing I ever did bar losing my virginity
b) i could never have done it if i hadn't picked up all of the skills i'd learn't in my two permie jobs. and that skill list is not limited to technical skills.
as mentioned earlier, client facing skills are essential. no one wants a monkey who will quitely sit in their pod/cubicle/desk all day tapping away and producing fantastic work if they don't feel confident in showing off the legend who created said fantastic work to their paying clients.