The PRFCT time
If there are bare areas in your lawn, reseed now, the grass can fill in and weeds will have no place to grow in the spring! But, don't over seed! Over seeding is the process of spreading seed over an existing lawn to fill in bare patches. How much seed to apply? Depends on the type of seed you are using. Look on the package for recommended rates.
Over seeding occurs when too much seed is applied over a given area. Why isn't more better? Too many grass plants growing too close together leads to over competition and die-off. In humid conditions, it can also cause mold and other fungus diseases like in the picture above. Gross.
If compacted: break up or aerate the soil.
Replace or amend poor soil with organic, weed free compost or new soil.