How to make specialized abilities more generally useful.

[SangoProduction]

As a player that is.

Something like Spellthief for example is pretty suboptimal if you're not facing spellcasters. Likewise, Favored Enemy (Orc) is pretty useless if you never/rarely face orcs.

Is there anything you can do as a player in order to make these specialized abilities more generally useful?

[Particle_Man]

As a player? Talk to the DM. Say things like “Since I am playing a Spellthief, could we have more spellcasters among our opponents?” or “Since I am playing a ranger with favoured enemy (orc), could we have more orcs among our opponents?”.

That said, another trick with spell thieves is borrowing spells from your allies (with their permission).

[Quertus]

Purchase spellcasting services, use Wish / Miracle to make sure your abilities see use?

[pabelfly]

It's hard to give specific advice without more information, but for Favored Enemy, I like to pick up Favored Enemy: Evil on Stalker of Kharash, since the vast majority of enemies are Evil. Swift Hunter is also good to use Favored Enemy to get skirmish damage against enemies otherwise immune to Skirmish damage.

[Xei_Win_Toh]

I'd ask the DM in advance, "is this campaign going to have enough spellcaster enemies to make Spellthief's abilities useful often?" or "Is there one major type of enemy that we're going to be consistently fighting against?" or at least "What are good favored enemies to pick for this campaign?" And if the answer is "Probably not a lot of spellcasters, they take too much effort to build and run as enemies" or "It's going to be very much a grab bag of enemies of all kinds", then I'd probably pick a different character concept than spellthief or ranger for that campaign.

Of course, for Favored Enemy in general, Pathfinder has Instant Enemy as a 3rd-level Ranger spell; swift action to treat an enemy as one of your favored enemy types for a minute/level.

[Telonius]

Yeah, this is something that really needs to be worked out with the DM. For things like Favored Enemy, the DM should really try not to invalidate a main feature of the class. If the Ranger takes Favored Enemy (whatever), sprinkle at least a few of that type of enemy in to make it mean something.

Alternately, there are a few potential changes that you could make, to make it more generally useful. There's already the Favored Enemy: Spellcasters ACF, if you happen to be facing a lot of casters. You could port over the Urban Ranger's Favored Enemy (Organization) as an option for the regular ranger. You could even use the rertraining rules to switch out which favored enemy you took, if you're no longer fighting hordes of Plants (or whatever you were fighting at low levels). All of those do need DM buy-in, but at least they exist in the rules already. If you wanted to make a more drastic change, you could take a tip from Horizon Walker and houserule the bonuses to apply in particular environments, rather than against particular foes.

I do agree that it's annoying, not to mention bad design, when a class gives bonuses to left-handed Oozes named Steve (but only on alternate Thursdays). Not every feature has to be something that's always applicable, but it really ought to be big or common enough to matter.