Tom Chick’s got a great post up on the “Seven Things I Wish I’d Known Earlier” with regards to Dragon Age. No spoilers, just stuff you should know. It’s well worth checking out if you are playing, or plan to play, the game. Here’s a snippet:
7) I wish I'd paid attention sooner to the tactics screens. Early on, before you're comfortable with the pace of combat, here's an important tip that I must insist you follow: For every character, and especially your front-line fighters, go to the character screen, select tactics, and insert a new first line that instructs the character to drink a lesser health poultice as soon as his health is below 50%. It'll save you a lot of grief, injury kits, and reloaded battles.
I’d say wait for 25% if you want to conserve health potions, but if you do that you do run the risk that a character will get knocked cold before they can imbibe. As Dr. Peter Venkman would say, “Important safety tip. Thanks, Egon.”