I started freelancing six years ago, because I came to the conclusion that I didn't like entering a building in the morning only to leave it in the evening, especially in summertime. My first contract job lasted two hours (I came to work on monday morning, only to find that three major clients had withdrawn their projects) and I when I realised I wasn't panicking, I knew that I had what it took to be a freelancer.

I usually manage to work three days a week, to have two days for my own research projects, but sometimes it fills up, which is, of course al luxury problem. I sometimes can take lunch in the city I live in when I feel like it, work from the balcony chair/hammock, and idle some time, but usually I work more than when I was still employed. Main advantages:
1: choose my own projects,
2: I am not a prisoner of my skills,
3: there's not much politics because I'm no threat
4: It's honest. You got some skills, if people like it you get payed, if not, you have to learn new tricks
5: Money ,marketing, web sites...you all do it yourself, and it all comes down to you. It takes time, and it helps if you know what niches you want to own.

Most important lesson: I like to live a simple life. If I make a lot of money, I put it away and forget about it until I need it. All economic theory aside, most wisdoms they put on tiles still hold: you can only spend money once, and after summer the winter comes. If you can't handle a lot of money that seems to waste away on a small interest rate, don't become a freelancer...winter WILL come!