If you have more than a few small spots to re-seed, then rent a slice
seeder, which is a lot faster and easier. Even more importantly, it
puts the seed in grooves, which is where it needs to be for good
germination. Use a starter fertilizer, get the PH tested to make sure
it is in the correct range, and use a high quality seed, preferably
endophyte enhanced.

For most of the US with cool season grass, it's way early to put down
pre-emergent crabgrass control. The optimum time is when soil temps
get into the 50s, a sign of this is about when forsythia's start to
bloom. For a newly seeded lawn, however, you can't use the
conventional ones. Tupersan, however, is OK for a newly seeded lawn.