What makes up a good stabilizer? Ive never used one before, what am I looking for? Things to avoid? Worth the investment?

What you want is a stab that will absorb vibration and noise. There are a ton out there that perform very well, but my 3 favorites are;

Carbon Impact Carbon Quatro
Fuse Axium
Simms S-coil.

Honestly, for 20 bucks, that S-coil is awefully hard to beat.

Great advice from mobow but also keep in mind that stabilizers were originally utilized to help with balance and aiming. Your best bet is to find a place that will let you try some out with your bow to see not only which reduces the most vibration but also which helps balance your setup as well. A perfectly balanced bow or one with the ever so slightest forward "tilt" is usually preferable for most shooters.

Alright another question for you folks here. I know Im full of them, its the curse of being self taught.

I see that stabilizers come in different lengths. How do I know which one is best for me?Why would I choose a 4" stabilizer over a 6" or 8" or even a 10" one though 10" seems like it would be more of a burden in a tree stand.

Ive never shot a bow with one thats why Im wondering what the advantage is.

Im sure if some of you saw my set up you'd be amazed that I can get deer, and almost all my tracks are under 100 yards.

There are two answers to your question. One refers back to what I said in my previous post. A longer stabilizer, or a heavier one for that matter, might give you a more well balanced setup and therefore should promote better accuracy. Two, it is going to depend on your preferences. Personally I do not like to hunt with anything longer than 6 inches as I find it annoyingly gets caught on brush, etc...