For any fertilizer to be most effective you need to first have the correct ph, most grasses like something between 6.5 and 7 (neutral). Ph test kits are relatively inexpensive and it is somehting you can easily do at home in just a few minutes. Take a small pail and get samples of your soil from a few spots around your lawn. Dig down an inch or two to get your samples and mix them all together in the pail. You take your ph test sample from that mix, that way you will have an accurate average for your first application. It's best to make your applications (lime or fertilizers) a bit on the light side. It takes a while for any correction to work in and is better to sneak up on an ideal with light applications than to "slam" the soil. If you have lots of pines, oaks or moss, you're likely going to need lime for a start ...probably lots of lime!
Finally cut the grass tall, for tall grass means deep roots
