Its pretty simple, the offset of the wheels provides the amount the wheel will stick out. A lower number, ie 15mm offset wheel will stick out compared to a 45mm wheel.
Camber adjustments are only necessary for performance driving, or tucking a large wheel which is truly far from fitting normally on your vehicle, like the style 92 7 series wheels.
If you want a flush wheel, you would most likely have to roll or cut your fenders, so the wheel will not rub.
1) Proper wheel width(not too wide)
2) Proper tire size(not too wide)
3) Rolled Fenders
If you don't want to lower your vehicle, you will possibly have a more obvious gap, due to more rim and less tire in your well, and the car will look worse than stock wheels, especially on the non sport models.
Best way is to slightly lower, and do the above three.
The moment you start playing with the camber adjusts, you risk excessive tire wear, and if your just a street driver, your not going to gain much. You will be more content with slightly lowering your car properly, giving you a lower center of gravity and better handling, you wont need more.