Check your mowing height. Make sure it’s not too short. I am in North Carolina with fescue and mow at 3.5 to 4.0 inches.
Get your soil tested and follow their recommendations. Your local extension office can help you with that. Lastly, make sure you are fertilizing at the correct times. Again in North Carolina with fescue one fertilizes Labor Day, Thanksgiving, and Valentines day. If you only do it once a year do it around Halloween.
If you have a weed issue, identify the weed and treat appropriately which means looking for the specific chemical that is effective for the weed you have. I have some nutsedge in my front lawn this year and am using sulfentrazone to treat it. I live near some Bermuda grass lawns and use triclopyr to manage the Bermuda that gets into my yeard.