I do a bit of a hodgepodge of what the previous posters have described. I make my TP without FP and figure out which 3 FP I want to get. If I haven’t been on the forums lately, I hop on and scope out which are the “hard to get” FP (right now I’d say that SDD is the hardest to get, followed by FOP, with a handful of others like SDMT trailing behind). I make a list of FP to try for, sorting first by difficulty to acquire and then by where they fall in the trip. So for example, if I’m doing MK, Epcot, AK, MK again, then HS, the list might go FOP, SDD, SDMT, PPF, BTMR, TT, etc.
For the ones that are likely to be a problem (right now SDD and FOP), I also think about what I’ll do if I can’t get them on the day/time I want. (For example: If I can’t get SDD on day 5, see if there are any on day 4 and if so switch the 2nd MK day with DHS.)
I make sure I get those hard-to-get FP first and then get the rest of the FP that I can.
I agree with this in theory. In practice, when I cannot get the FP I want on the day that I want, I end up rejiggering plans and re-optimizing/reevaluating to figure out the best thing to do next. I try not to do that until I secure the hardest-to-get FP, though.
One final tip: if you can’t get a FP you want anywhere near the time that you want it, you may want to consider grabbing what you can and then try to modify it a bunch of times to see if something earlier pops up. (Balancing the need to get other FP - you don’t want to spend so long modifying that you miss out on reserving other FP you want at the time you want them.) I think that this is usually done day-of in the park, but I found it worked well for me for FOP two months ago when it was my FP day. If you’re making your FP right when they open, so are a hundred zillion other people and they’re making and changing their plans at the same time as you are. I think I started with a FOP FP for 5 pm and was able to modify it up to 2:50. Still later than I wanted, but doable for my group.