Annie, one of the quick easy ways to raise humidity is to use plastic ripening boxes (I call them "minicaves") which retain the moisture given off by the individual cheese, thus raising the humidity around that one cheese. I have several in use in my caves right now. Since I am currently ripening some blues (Fourme d'Ambert cheeses) they require a higher level of humidity than the inside of my caves can offer.
I'm having a problem keeping my Camembert rounds at a low enough temperature and high enough humidity. I bought a combination temperature/humidity gauge which has a remote probe, so I can read both outside the cave. I finally moved the Camembert to my refrigerator (45°F), inside a plastic container, and even put a wet cheesecloth inside next to, but not touching, the cheeses. So far, humidity doesn't get above 50%. If I put them in my Styrofoam "cave" in the basement, I get 85% humidity (still not enough), but the temperature goes to 60° or more.
What are your "plastic ripening boxes"? Are they just plastic containers like one can get at Walmart? Or something different?