Do you know how to orchestrate already? If not, buy this book;
http://www.amazon.com/exec/obidos/tg/detail/-/
0130407712/002-6461678-...
That book will teach you a whole lot about orchestration. Better yet, I'd take a class in it at your local university. Orchestration is a fascinating area of study.
However, in my experience (which is almost nothing) I had to know basics before I could get any work done. Oh, I suppose if I wanted to put some techno music together I could just push some buttons without knowing a blessed thing. That's probably one of the goals of techno music anyway, why not? But orchestration is a little more complicated.
Study it, you'll love it.