http://www.buzzerbeater.com/community/forum/read.aspx?thr...this link is the training speed grid, it is an approximation, but this is how fast your players will train... but keep in mind that players train faster if they are younger.
http://www.buzzerbeater.com/community/forum/read.aspx?thr...this link is the potential salary grid, which means that based on the potential of a player they can only train so high, until they significantly slow down in training.
http://www.how8.com/bb/index.phpthis link helps estimate someones salary (this is useful because players salary only update each season (approximatly 3.5months))
But basically the best way to train players, is to
Single Position Train two players. Somethings these players should be is 18, with High potential, and around mediocre to respectable in their primary skills.
As a beginner, I would recommend training Two Centers, that are at least 6'10'' and 18. with at least perennial all-star potential.