That seems like a no-brainer, but many people think they can grow a showpiece lawn with bargain-basement grass seed. Bargain seed contains empty seed hulls, stems, and too many weeds. Select a quality seed that is 99.99% weed-free. Also, quality seed is the product of extensive research, giving you grass that can withstand the extreme conditions in your area. Starting with quality seed simply means less work later.
You want grass seed to make good contact with soil. So you need to rough it up a little. Loosening the soil also helps tiny seedlings to take root. So rake your lawn, and remove any dead grass in the process, before seeding.
Grass is like any other plant. It needs soil, moisture, light, and nutrients to thrive. That's why seedlings need some room to grow. While it's tempting to pile a whole lot of grass seed on a lawn or bare spot, doing so just creates a free-for-all. What grass manages to grow will be weaker than it would be if you had given it some space. Just use the spreader settings on the seed bag for good results.