Other than the obvious, of course.
I have been making this play through all about trying out the various NPCs and their personal quests. Which, interestingly enough, is why I'm in the spot I'm in now. I picked up Nalia fairly late in chapter 2 and I want to complete all of the fighter stronghold quest with her in the party. (RP-wise, I want to ensure she is safe from the Roenall scum before leaving her in the keep). The trick is that the party has done all the easy stuff and is now moving on to harder quests that really need a decent thief. Firkraag's dungeon being one, but also the WK and few areas in the sewers. It was actually WK that made me despair a bit, as she not only couldn't unlock some of the chests, she couldn't disarm the traps either. I ended up having Mazzy be a damage sponge.
I really want to avoid using EEKeeper to stat jack, so I'm trying to work out in-game ways of getting around NPC limitations. However, Nalia is proving to be a challenge, as a certain level of thief skills is practically a requirement. I do have her memorize as many knock spells as she can, but that leaves traps. At a certain point, Jaheira, Aerie, and a buffed Mazzy/Isra can take over the thief role, though with far less finesse. I also know there are a few traps that can permanently trap/imprison a NPC, so having Mazzy be a sponge isn't a very safe option.
I do have some potions of master thievery, but I keep thinking I should save them for later in the Underdark. Maybe the solution is to just get a bit more free with those?
While I do like Nalia, I have a sneaking suspicion that as soon as that stronghold quest ends, she's going to get a nice, relaxing break from adventuring.