Playing a tournament in absolutely perfect conditions is like that mythical annual vacation at the beach where everything goes perfect. But life is not a beach vacation, and neither is table tennis. You not only should be prepared for poor conditions, and as players, you should expect them. This doesn't mean you should just accept them; by all means work to make sure tournament and club directors have great conditions. But as players you have to adapt to the playing environment. Tactical players adapt; non-tactical players complain. Here's a short primer.
First, have a good pair of table tennis shoes. They are designed to give the best possible traction. Make sure to have a new pair as worn-out ones won't give as much traction. Many players who play at clubs with good floors get lazy on this, letting their shoes wear out, and don't realize this until they are stuck on slippery floors. I suggest getting news ones for such tournaments, and use them only when needed, until the ones you use in practice are falling apart.
Second, step on a wet cloth between points. Watch the top players and you'll see this all the time if they aren't playing on good floors. It can be a wet paper towel or a cloth, it doesn't matter. You'll get much better traction after stepping on it for several points.
Third, use it to your advantage. Players can't move as well on slippery floors, so move them around!
And once again, use it to your advantage. If the lighting or background is poor, it's harder for players to follow the ball. This favors attackers, since defenders are trying to pick up on a fast-moving ball. This doesn't mean wild attacks, but when it's harder to see, play a bit more aggressively, and expect shorter rallies.
First, make sure to have a dry towel to dry your racket and the ball off with. If you sweat a lot, you should bring two towels, one for you, one for the racket and ball. Then use the towel(s) a lot, making sure the racket, ball, and your hands are dry. (A wet non-playing hand means the ball gets wet; a wet playing hand means you can't grip the racket very well.)
Second, adapt tactically. You won't be able to overpower an opponent with spin, so loopers have to either go to more drive loops (sinking the ball into the sponge, and so less spin, more speed, not as consistent), or steady loops where you mostly keep the rally going. Hitters and blockers have the advantage here, so you might do more of that - but often they too have problems with the humidity as it changes the friction on their racket, and so they block loops into the net. One of the most successful ways to play in humid conditions against a looper is to simply dead block over and over, and watch the poor looper try to loop with any effectiveness.
Finally, a reminder - when faced with bad conditions, you can either surrender to them and lose, or take advantage of them and win. Save the complaining for when you aren't playing, which usually means after the tournament is done.