How to unlock familiar abilities

[Michael New]

I see the list of familiar abilities but it's unclear to me which one a given familiar might have, and how to get more. For instance, what familiars would know a language, or have darkvision? Which ones would fly at 25 and which at 40? Are there other rules about familiars I haven't found?

[Xenocrat]

I don't think any animals would have natural darkvision or know a language (maaaaybe a parrot). Negotiate anything you want permanent (like 40' flight speed as a hawk?) with your GM. But the wisest course is to pick something that doesn't have any special abilities so that it's entirely customizable.

[Fuzzy-Wuzzy]

You pick which two abilities it+you get each day. Any familiar could speak a language, have darkvision, etc, as its master pleases. Any master who prepares cantrips could get the ability to prepare an extra one, etc. The total #abilities between you must add up to two (unless you have a feat or something that increases it; I think it can get up to four).

The only restriction is that if your familiar is a critter that inherently has some ability (e.g. birds can fly) then you must pick that ability as one of the two.