One thing I tend to do to deal with traps and similar problems:

If an area looks dangerous (dungeonlike caves, spooky swamp, pretty much all of the Underdark,...) I will often split Astarion (or whoever else is good at sneaking about) and have him scout ahead with the rest of the party trailing behind.

I anything blows up, it only blows up one person.
If there are potential enemies my rogue will find them, before they find my rogue. And I also get a good view of the terrain.
If there is nothing to fear the rogue will just loot the whole place and reunite with the party.

Also: If you find a group of people and you are not sure if they are friendly or not, just sneak your people into position anyway before talking.

For example: At some point in the game I met some Kuo-Toa and they seemed kinda fishy. So I had Astarion sneak behind one of their archers and positioned Gale on a high-ground, before even approaching their leader. I ended up not fighting them, but if I had, I sure would have been glad about that positioning. So, you can't be to careful there.