For the natural guy, it's best to stick to only 400 to 1000 clean cals over maintenance level -- whatever amount you eat to neither gain nor lose.
Better to start with 400, then go to 800, maybe go to 1000. This will give you the surplus needed to fuel muscle growth without too much spillage into fat gain. Most of those extra cals should be in the form of peri-workout stuff, like Surge, etc. That way they're "put to work" rather than stored as fat. Keep insulin high around lifting time for muscle gains, then lower the rest of the day to prevent fat gains. Clay Hyght's last article goes into that. You can find it in the recent article archives here on TNation. I think he's spot on.
I also like to use tape measurements, especially around the belly / love handle area. That will give you a more accurate picture of "weigh gain" -- the scale can't do that; it just gives yuo a total. Ideally, the scale weight goes up (muscle) and the tape measurement stays the same or barely creeps up (not much fat gain.)
Pretty general, but I hope that helps.