Mixing Camo and Solid colours
 

What do you think is more effective and looks better?

Solid pants with camo top or camo pants and solid top?

I've seen both pulled off quite nicely. If you want some pics for reference, just look up the Norwegian Telemark Battalion. Plenty of those guys seem to mix the two.

If you're set on mixing, then camo pants with solid shirt.

Try to match the colours on the camo pants
Like woodland pair with olive drab combat shirt or a coyote brown, multicam with tan shirt etc

For fashion camo pants and a shirt in a colour from the pattern.
For field use it doesnt really matter, just match to the background.
So at this time of year in your basic Ontario woodland area brown, tan, woodland, MC etc.. bottoms and OD, woodland, Atacs FG, etc... top as the cedars and pines will be green as will many of the tree however youll be in dry grass or muddy, leaf liter and damp areas where the forest is older so you will blend in just fine with brown or tan bottoms and green tops even without a pattern but a pattern does help against a lot of observers but some can pic out your pattern even so YMMV

It all depends on where you play, adapt your camouflage to your AO.