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.
LatinTutorial (website) or LatinTutorial (youtube): great at clarifying difficult grammar
Hexameter.co: good practice if you're new to scanning hexameter
AP Latin is not a popular AP subject and its resources are very limited. The main thing is to read the assigned readings in English and to translate as much as possible. For that, you don't really need anything besides a dictionary, a copy of Virgil, a copy of Caesar, and ideally a copy of another Roman author, since the AP Latin exam MCQ section also tests students on readings outside the syllabus (e.g., Livy, Ovid, Pliny the Younger).
Free online edition of Virgil's collected works, translated into English