My best decision was going out slower than 1:25 pace. My original goal was to break 1:30, so I started at about 1:30 pace. I believed I was in 1:28 shape.
It was one of those times I was glad to have underestimated my fitness. By running the first three miles in 6:45's (with mile 1 at about 7:00), I set myself up to be in great shape over the last 10k. I was able to ratchet up the pace gradually. Had I gone out faster, I think I would have held up OK, but probably would have topped out at 1:26 or so.
I just looked back through my training logs, and I was amazed by how... average?... my training looked. I consistently got my long runs in and hit one faster workout per week. I had a foot issue pop up the last couple weeks so I had to taper dramatically. I think this helped me feel rested for race day, with the exception of my impromptu hard session several days before.
I was also incredibly psyched for the race. That's a variable that's hard to quantify. I just had a fire under my @ss.
If you've done a consistent dose of long runs over 10 miles, have sub 18:30 5k speed, and get a few shorter, sustained, hard efforts near race pace in, you've done what you can. My best decision was protecting my weekly long run at the expense of everything else.
I then went from this race to an attempt at sub-3:00 for the full marathon the next year, which I bombed. Running is funny that way.
Good luck!