A tent shell causes a convection effect - warmer air rises from you (especially from respiration) and cools when it contacts the tent interior, which is cooled by the outside air. Some of the cooler air passes outside, but some of it settles back down on you and the process repeats.
You can reduce this process in ways explained above: notably, opening the tent as wide as possible to air currents. Opening ventilation windows will break up the convection effect and deprive the warmer, rising air of a surface to dump its moisture on. Because the tent doesn't provide much insulation, you really won't lose much by doing so. Your sleeping bag is responsible for keeping you warm and cozy on such nights. It goes without saying, incidentally, that in humid conditions like that (or where I live, on the East Coast of the USA), you should be using synthetic sleeping bags and clothing as much as possible.
Another thing to do is to experiment with your use of the rain fly. At points where the rain fly touches the tent, condensation tends to occur more because less moisture-laden air escapes through the waterproof fly. At places where the fly does not make contact with the tent, but sits a few inches above it, moisture condensing on it tends to follow the contours of the fly off the top of the tent and then down onto the sides. This speaks to two things to look for in a rain fly and tent construction when making your next purchase: (1) the fly ought to be long and broad, not one of those dinky little beanie-type things; (2) it the fly ought not rest on the body of the tent, but on the poles, held away from the tent.
If your rain fly fails in these regards, rather than rush off and buy a new tent, try getting a tarp and hanging it over the tent across a line and anchoring it on the corners, like a big A-tent close over your tent. Then keep your tent as open as possible to ventilate it without letting in rain or uncomfortable amounts of wind. I've never tried this idea because my Sierra Designs Omega is awesome, but I'd like to know whether it helps. I'm convinced the theory is sound.