Welcome and good luck. I would just echo some of Endrews comments
Don't start too big: I just re-released my first story, it was supposed to be a very small demo just to work out the system but turned into a much longer one with several entirely different paths. This meant it took me months to get it edited and workable instead of days, so start small until you know the system.
If your going to use the advanced editor read up on it first!
Space the writing out and careful of bad links. if each page is only 1 sentence it will annoy everyone, also if it is 6 pages of text leading to 1 link it will annoy people (instant death links also = bad)
Mainly though have fun!