There's a thread in Mesaboy2's profile signature link (I think), were it has the FP+ tiers for each park and recommended priorities which is very helpful. You'll need to set up an
MDE account, link your tickets to it, and then you can pre-book your FP+ choices through it, once you get to your 60 day mark if you're staying onsite. If you have a smart phone you can download the MDE app, or you can do it through Disney's site. I'm sure I'm missing some info on it which I'm sure someone else can help you with. Meet and greet with Anna & Elsa and the new 7 Dwarves coaster seem to be the top 2 attractions to book and advised to book them at 60 days out for best availability. If you're staying offsite, I think it's 30 days out from your vacation.