If you are serious about having a beautiful lawn, your journey MUST start with a good soil test. If the ground is not frozen where you live, then you can collect soil for a test. Many people wait until just before the new lawn season starts, but, why wait when you can get it over with and done now. So when the Spring arrives you are ready to hit the ground running.
Take a look at my latest YouTube video for a quick tip on which soil tests you should consider.
https://youtu.be/fEl3WAiKk