Use this website: http://www.scrabulizer.com/
Unlike Scrabble-solver or any of the others, you can tailor it to Alphajax specifically. Not only that, but if you fill in the board with what your current game is, the Scrabulizer will actually work out the very best possible words you can play and list them in order of points.
Using this, I haven't had a word lower than 25 points for the last 20 plays
This will get you the maximum amount of points in every game you play.