Grass seed will only thrive in balanced soils. Knowing your soil’s condition requires you have the results of a lab-based soil analysis.  Be sure pH is in proper range (generally between 6.0-7.0)  Only purchase high quality seed.  Check the tags CLOSELY.  Germination rates matter, no noxious weeds, blends vs. single cultivar seed and confirm current harvest dates.  Be sure seed comes in direct contact with the soil and keep the sown areas moist for three weeks after germination.  Don’t let the soil completely dry out.