I wouldn't give any besides stuff like: if elves in your world are all kinda "good" characters, they'd not be warlocks. Or if you have some evil species, they wouldn't work well with a class "Paladin" except it's a paladin for an evil deity. I wouldn't add any additional hurdles. If you have fitting attributes, you should be able to pick it... fitting as in: if you have intelligence 5 and intelligence is what you need to cast, you better not be a caster then. :-P
Also again: flair. I like for everything if a play can put their flair onto it. I have an archetype/class "Warchef". That could be a flair of an "alchemist". Creating tiny cakes and snacks instead of potions.
I wouldn't give any besides stuff like: if elves in your world are all kinda "good" characters, they'd not be warlocks. Or if you have some evil species, they wouldn't work well with a class "Paladin" except it's a paladin for an evil deity. I wouldn't add any additional hurdles. If you have fitting attributes, you should be able to pick it... fitting as in: if you have intelligence 5 and intelligence is what you need to cast, you better not be a caster then. :-P
Also again: flair. I like for everything if a play can put their flair onto it. I have an archetype/class "Warchef". That could be a flair of an "alchemist". Creating tiny cakes and snacks instead of potions.