Spring Yard cleanup is just about here. One of the more frustrating problems of living in the pacific northwest is moss invasion.
The way to prevent moss from building up too much in the grass is to keep it well drained and aerated. There are inexpensive aerating tools which are just a tube of metal that pulls plugs out of the grass as you stomp on it. This is what I use. It has the advantage of letting me wiggle it a bit in areas that need a bit more loosening up. But if you have a large yard, you will soon get worn out.
For a large yard, the better bet is to go to the rental store and get a gas driven aerator which is about the size of a lawn mower. If you coordinate this with a few neighbors, you can split the cost. It is a fast effective way to aerate and you can get the whole neighborhood done in an afternoon.
After aerating, apply a topping of sand and try to get as much as possible in those holes.
If your yard is heavily infested with moss and other weeds, then a good power raking is called for. And yes I know this is controversial, but ask any reputable professional gardner and they will tell you that a good power raking is the best solution for a host of lawn problems. Yes it looks ugly and the neighborhood will think you have gone mad, but this will give new grass seed a great chance to establish and crowd out future invasions.
Apply a good moss killer and also sweeten up your soil. I like to use dolopril as a ph sweetener because it is easy to handle and apply. I also like to use a liquid moss killer for the first application. There are combination fertilizers and moss killers on the market. I use these after I have hit the moss hard with a pure killer.
Now it is time to top seed. If you have a moss problem, then chances are that you are in a shady area. Make sure to buy grass seed appropriate for your specific area. I actually like to apply different seed mixes for different micro climates in the yard. Yes there will be a slight variation in green color, but at least I will have grass! Check you seed blend. Buy grass seed that has a higher percentage of perennial and creeping varieties. You won't get the instant satisfaction of the quick sprouting annual seeds, but you will get better resistance to moss and weed invasion during the wet shoulder months.
Apply fertilizer appropriate to the stage of the grass growth. You want to get strong roots and thick foliage. I've found that varying the fertilizer works better than just laying down one type for the season. Even if I use a slow release product on an established lawn, I will still top it up with the occasional boost of liquid fertilizer in areas that show need. For example, my trees such a lot of nutrient away from the grass.
So to sum up: Aerate, sand, kill, rake, sweeten, fertilize, seed, and pay attention to micro areas.
The first four points are vital, and unfortunately for us in a rain forest climate, a yearly chore.
Good luck with you lawn this year.