|what is the best type of fertilizer|
|Ideally you would run some basic soil tests and check the fertility and also the pH and then fertilize and/or apply lime based on the soil test results. Without testing, there is just no way to tell you what would be "best". Your local Cornell county extension should be able to help you with the testing and interpreting the results with the goal of growing healthy lawn. In the meantime, you may find the lawn care information at their web site helpful.
Good luck with your lawn this summer!