There can be several factors that affect non-neutral surfaces, but when a plane gets closer to trim and balance, if everything is straight, the surfaces are true/trim/neutral as well..
Incidence is definitely a part of it, and should be set accordingly, but it's adjustment isn't the whole picture. Balance(fore/aft/left/right), thrust angles(pos/neg/left/right) obviously have everything to do with trim as well. Balance will affect elevator trim as much as incidence might.
I try to get my planes trimmed so everything is at neutral. Even if the surfaces might be off a few thousandths', for the most part you can't notice visually that any surfaces are anything but true and neutral. If they're off any I don't see it, and the real test is in flying and testing.
There's a popular trim guide written by Peter Goldsmith that takes you through a series of manuevers, and explains what/how to go about getting a plane dialed in. I've found it invaluable and have used it for years. I suggest you Google it and see if you can find it and give it a read if you can.
I'm also going to take speedracer's advice myself and check out his recommendation.. You can never have too much information, and everything in this hobby is a learning experience.
