Two things:
1.) Save money while you're young. Keep living like a college student for 5 years after you leave college and sack away at least $10k/year. Put it into the market and don't touch it again until you retire.
Compound interest is quite a thing to behold, and 5% returns over 40 years will do some amazing things to your money. Start with 100k when you're under 30 and you probably won't ever need to worry about retirement savings.
2. Get to the point where you are provably good at what you do as fast as possible. This will mean switching jobs several times. Build things that are noteworthy and get to the point where people are recommending you to their friends.
Once you've done that, you get secret point 3:
3. You are more valuable to your employer than they are to you.
Companies spend a lot of effort making you think your job is precarious and could be taken away at any minute. In reality it will take six months to find a decent replacement for you. Once you're in and demonstrating that you can find your arse with both hands, they're not going to want to lose you.
That gives you lots of room to explore, and is the reason that I love this industry so much. I can't think of another profession where you can take nine months off every year and still make a good living.
More here:
http://www.expatsoftware.com/articles/2007/02/two-weeks-vaca...