Have a look at Digren's guide:
viewtopic.php?f=3&t=29733Starting off, I agree with Digren and would tend to match socket bonuses and go for things with mastery:
Yellow/prismatic - mastery
Blue - mastery/stamina
Red - mastery/parry
As you get better gear and reach 102.4% combat table coverage, most people start to regem to stamina.
There's a case for ignoring socket bonuses when stacking stamina - theckhd has posted some useful information about the trade-offs:
viewtopic.php?f=3&t=32711For PvP, it's a whole other ball game. For casual BGs, I go for strength to help kill stuff, but dedicated flag carriers in rated BGs etc would go resilience.