How To Avoid Chess Blunders?

Recently I've been thinking, "How to avoid chess blunders?" Take, for example, the following position which occurred between Emanual Lasker and David Janowski in their World Championship Match:

Janowski blundered with 19. ... Rd6? Play went: 20.Rxd5 Rxd5 21.Qxd5 Qxb4 22.Rxc6 1-0

In order to avoid blunders, it may be useful to think, before the move is made, "After I make this move, are there checkmating threats against my king?" Also, it might be useful to think, "After I make this move, what would happen if exchanges are made?" It seems to me that not just this example, but in other examples, blunders are refuted after exchanges.