Oooh. Here's a few tips everyone playing should know. I ripped them off of Tom Chicks post a few pages after the one Mauxe pointed out. (thanks for the site Mauxe)
1) Since I'd rolled up a Dalish elf - they're the outdoorsy variety - I figured I'd bump up her herbalism skill to keep my party in potions. Only later did I realize that one of the NPCs you can't miss starts out with the second level of herbalism. And unlike poison-making, which limits who can actually use poisons as well as make them, you don't need herbalism to benefit from better potions.
2) The game seems to go out of its way to include locked chests. I've missed a lot of treasure for lack of someone with the deft hands skill. Since my character was a rogue, that should probably have been me. Instead, I end up compulsively going back through a lot of areas with a deft handed rogue in tow just to unlock the locked chests. It's probably a bit compulsive of me, but I've found some good loot I wish I'd gotten the first time around.
3) I wish I'd put at least a point into the coercion skill to leverage my cunning or strength for the persuasion and intimidation options that come up during dialogues. As with the locked chests, I was surprised with how many of these there were. And since I already had a high cunning, at least a single skill point would have made that cunning all the more useful.
4) There will, of course, be times that you're adventuring alone for some contrived reason. That's to be expected in these kinds of games. But I wish I'd known that one such time would involve me being unable to summon the corrupted spider I had invested four skill points in getting. My character has the ranger specialization maxed out, so she's been relying on a bad-ass spider to make up for her lack of melee skills. That spider was inaccessible during a stretch of gameplay that proved particularly tough.
5) I finally dealt with my inventory problems by resigning myself to never using any of the elemental resistance potions, poison coatings for weapons, or gear for one of the two party members who uses specialized gear. If I'd made this decision earlier, I would have been able to tote more loot back to camp to sell and would have had more money to buy goodies.
6) Whoa. Grenades are awesome. They played a big part in the combat in Mass Effect, but little did I know they would be so useful in a fantasy world! I slogged through many a battle that would have been a lot easier if I'd appreciated sooner the value of a judiciously applied acid flask or shock bomb.
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.