I am sure you know this, or have at least read it before, but be prepared to spend money and possibly alot of DIY work.
I have wanted to setup a SW tank since I was 13. My parents were convinced it would be too complicated and expensive so they wouldn't help me. 3 years later with what little birthday money I had I decided to try setting up a SW tank. My grandma bought me 10 lbs of live rock from here. I had new cheap power heads and a box of instant ocean salt for up to 20gallons....well I quickly ran out of money, had my tank setup for the next half a year with nothing in it but water and rocks, ran out of salt, was sick of topping it off everyday and making no progress, no one would help me out with money (=P) and it's hard to find a job without a license and both your parents working....got frustrated and gave up. EVERYTHING got thrown out.
Another 3 years later and I am now in the process of converting my old 55 gallon cichlid tank to a SW tank, I about halfway there but I have already spent a good $300, and have much to go.
If I can offer you any advice at all....be prepared to spend money, if your an impatient person dont even bother, go to the top of this page and read the 101 tips, and look through the other post as well....read then and reread them.
To start off though, you should focus on learning the nitrification cycle.
Learn about your choices of water. Everyone here would recommend you to get an RO/DI unit, I would buy one before you consider buying anything else, it will play a major role (I still have yet to buy one and wish I had while I still had money)
Buy a refractometer not a hydrometer.
Use sand, not crushed coral (CC)