I generally go for around twelve A4 pages to a chapter which works out to about 24 pages in a book. And I'm looking at say 12 or so chapters which would work out to around 300 pages for the entire book.... give or take.

But, its only part one of a trilogy. Trilogies are easier to market for publishers because they don't start to collect anything serious from your book sales until the 3rd book. That's what a published friend of mine told me.

I also have another trilogy in mind that can follow the first one I am doing ultimately turning it into a 6-part series.... ala Star Wars. But I can get away with just the first set of 3 books because they can stand alone without the addition of the second set.

So basically, if I get the first 3 published and they get popular and sell enough copies I'll put up the next 3 to follow on.