So the carbon fiber exhaust system like they said is a great thing, helps with ventilation and smell. However, you can attempt to vent the area around your grow room, add a few fans, you defoliate any unnecessary leaves that are pushing out water, also when you water you could water with less(soaked or soggy soil puts out so much darn moisture) make sure no excess water laying around in trays etc, AC units tend to lower humidity and some even have a built in dehumidifier. Or you can buck up and buy a small dehumidifier somewhere in range of 30-60$ especially if you're planning an HPS setup a dehumidifier may become even more essential.
Best of luck to you.
Is the region you live in one with a high RH over like 50% regularly?