I've just got my Apache, first timer with helicopters too. I need to pick up some paints for it next week, and I was about to ask the same question until I seen this thread. I did check the Humbrol/Airfix websites which lists the colours 'suitable' for their suggested scheme;
http://www.airfix.com/airfix-products/deleted-items/a03077-boeing-ah64-apache-longbow-a03077/?searchguid=201338164529&resultspage=&sortorder=
So I was going to base mine off these, I assume every single colour probably isn't needed though, so maybe someone can give a better answer in this thread.