Most of the treasure your PCs find should be what's on the bodies of their enemies. Accordingly, just figure out the individual wealth of each enemy and kit them up with the gear that would be useful to them. That would mean weapons, armor, wands, and potions that they can (or intend to) use to try to stay alive. It's pretty ludicrous to find a bunch of combatants using mundane weapons and armor (and losing) when there's a bunch of treasure, including a set of +2 chain mail, just lying in the corner of their cave. If the PCs win quickly they'll get a bunch of useful stuff. If they're less efficient the enemies' consumables may be diminished.

Occasionally you can mix in particular items which suit your PCs' needs, like that Ring of Evasion your Bard has been wanting. That doesn't mean things will work out the way you intend. Maybe the enemy character with the Ring of Evasion is able to avoid the Bard's spells because of it and runs away. Or maybe the other PCs decide to dice for the treasure and the Bard loses out. Don't get too attached to your plans regarding treasure. If you follow the standard tables and populate your world with the right amount of treasure (on average) per encounter, you've done your job. Attempting to micro-manage PC wealth is heavy-handed and generally leads to player resentment, even when you're trying to help the PCs out.