Some great tips here: https://www.hometalk.com/42162870/how-to-grow-grass-for-a-lawn-the-neighbors-will-envy
Try this article, Patty:
If you have a lot of trees in your yard, they are taking all the water and nourishment. The roots go out to the width of the canopy. Might do some digging around to see if you have grubs in your soil. they love roots.
After all this, might want to get a good fertilizer to sprinkle down.