Lots of good advice here. For me, success has been with a loose soil bed. Can't be over compacted. Spread the seed, then rake or drag to get seeds slightly covered. Then, ROLL IT! Rolling makes a huge difference, I think it gets the seeds in good contact with the soil. Keep damp and go from there. Covering with mulch helps a lot too.
Mutt lawns are funny, mine is super mutt! Just no way to keep it pure with the patching I have done and the neighbor lawns. But that is OK.
I am a little different on fertilizer. I hit it right when the snow melts, then one more time right before it comes in heavy with the first nice weather. One more shot middle of summer and then a good shot after it is dormant in the fall. It is amazing how much greener my lawn stays this way. I don't go super heavy and use cheap fertilizer but it works. A nice rain in August after my mid summer fertilization and it's as green as it was in the spring. And this is without a sprinkler system...