<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by kgm0001:
I'm attempting to develop some techniques to better the chances for an upgrade. I usually travel between San Juan through Newark to Los Angeles and back.</font>
Part of your strategy could include changing your routing. Transcons tend to be highly competitive. So avoiding EWR-LAX and routing SJU-IAH-LAX may improve things.
Also, search for non-BF equipped 757's that have 24 F seats up front. While not as desirable as actual BF seats, with 24 F seats on this type of aircraft, you have better odds of scoring the upgrade.