Please note: I do not own and have not paid for anything listed below. They can be found open access on the internet.
As always, use the past exam questions on the official College Board website.
Albert: subject explanations, practice sets (paid), blog, etc.
Heimler's History: useful FRQ writing tips.
The Western Tradition: a series of videos made by a former UCLA professor, each providing an overview of one APEH topic. The series is a little dated but does a fantastic job in terms of synthesizing each topic's information. Highly recommend.