A 90 is a LOT of helicopter and they cost a pretty good buck to keep in the air. I normally tell people the 50's are the way to go, especially for your first nitro. Most people (me included) with 90s own and log far more time on 50s because they are no where near as expensive to crash (about half) and consume about half as much fuel. I was going through a gallon a day when I had my 90 Avant.

Just some food for thought, not trying to discourage you.

Other than that we would need more information to give you specific advice.