hide the clock. The clock makes you rush the moves. You still play against it but don't see it. It is one of the options.
How to get better at tactics trainer.
To be honest, I kind of think that it's possible to get higher scores on the Tactics Trainer by "half-guessing" if you will. I don't mean just looking at the first queen sac and doing it, but if it seems like it's likely that a certain move will come out well, even if you don't see the precise conclusion of the tactic, you can still often be right. It's typical to play a move that seems like it's the move, and only find the rest of the combination as you play it out. On the trainer, this is of course a tempting thing to do, since whether you check the problem or not can make all the difference in the amount of points you get.
But does this really help you? Guessing if a tactic will be there? I think you should try to only make a move if you can confidently say to yourself that if you had that position in a tournament game, you would actually be comfortable playing it, given how much of the combination you saw. If you would be a little shy about giving away your queen in a real game after ten seconds of thought, I suggest to actually calculate the ensuing play a little bit! It might not get you more points, but you will actually learn the tactic and go through the discipline of calculating with precision. It will make you feel more responsible for finding the correct idea -- exactly the kind of disposition one has in a tournament.
I've been practicing a lot these days and I just dropped 400 rating points on Tactics Trainer. Can anyone give me some tips on how to get better?