Tactics Training Qaugmire

I have just joined the site and trying to get back into playing and learning the game and strategies.  I had been using Chess Mentor a lot but started focusing more time on the Tactics Trainer.  It seems that no matter how hard I try, I can't get and stay above 850!  Now, I usually only do a few and come back to it later and sometimes when I start cold, I lose the most points (at which the tactics seem to get easier because my score has dropped so much!).  Just wonder when I can break 900 and stay above that!  And wonder what all this means as far as what kind of player I am.