APs are a real wildcard. There are lots of strategic ways to play them, there is not one "right way".
Prioritization is important, both in terms of how valuable the recruit is, and when the recruit wants to sign. If you're going after a 4-5 star recruit who wants to play, and wants to sign early, that's where you better go big right out of the gate. You know he'll get attention from top teams, and he'll get it early. The only "considering credit" you get in 3.0 is for the promise of minutes for players who have the "wants to play" preference, so you want to unlock promises as soon as possible.
Beyond that, whether or not you max on APs for a player is basically a function of how willing you are to take walk-ons. If you value team depth, and filling scholarships, you will want to spread your APs around a bit, unlock recruiting actions on more players than you will end up signing. If you're ok going boom or bust, feel free to max APs, and roll with the big boys. Just make sure the player is worth the gamble.