A lot depends on what equipment you're using. If you're growing on the cheap, you can make a DIY odor sink.
Holes in the upper part of the bucket allow air flow. The 8" fan was taken off its stand and caulked with silicone seal into the top of the bucket. You use those round, solid room deoderizors in the bottom. It worked pretty well for my Sativas.
I also have a double window fan facing outward to vent and move air, plus fans in each grow unit.