The first thing that you need to do is to remove all the existing weeds and its roots from your backyard. This is tough work and would take many days to complete unless you have extra helping hand from someone. Using the back of a hammer as a pulling tool, you can easily pull out the weeds without hurting your fingers. When i was pulling out some weeds myself, i had a pair of rubber gloves on but those weeds with small thorns are merciless and poked through my rubber gloves and made my fingers bleed. Use the back of the hammer for pulling out such thorny weeds.
Secondly, depending on the quality of your garden soil, you might need to remove and throw away some useless dirt and soil (I mean if the soils doesn't hold water properly and is dry as well as hard most of the time). Use fresh top soil which is not too soft and not too hard. I bought my garden soil from Home Depot for cheap and i also added some good mixes of organic fertilizers, humus or peat moss, compost to condition the soil. Even though grasses can grow in poor quality soils, they need good quality soil to flourish and grow thick lush green color.
Use a long raking tool to mix and level out the soils which will make it easier for grasses to grow and breath properly. Finally throw in the grass seeds and there is no need to cover the grass seeds with soil for it to grow although you can cover the grass seeds half inches if you like. No need to worry about the birds, insects or other animals eating the grass seeds because for me, i didn't see or observe any grass seeds being eaten by those animals. For some reasons, animals didn't eat up the grass seeds and this allowed the grass seeds to grow in two or three weeks time. Grass seeds needs the proper temperature and proper sunshine to grow its seedlings. I found out that some areas in my backyard where sun wasn't reaching, the grass seedlings grew quite late and quite small. The others areas of my backyard which was receiving plenty of sunshine, the grass seedlings grew so fast and so big. I watered them equally throughout the whole area. This shows that sunshine is important for growing grasses.
October and November during the fall season is the best time to plant the grass seeds because at those times, most of the wild weeds are either dead or starting to die off which allows the grass seeds to absorb all the nutrients from the soil and grow unhindered by those wild weeds. Once the snow starts falling, the newly grown grass wouldn't die of cold. In fact, this gives a chance for the grasses to strengthen its roots during the deep freeze. The thick snow will keep the grass warm and still allows it to be alive throughout the harsh winter.
Once spring sets in, you will need to reseed your grass lawn with new grass seeds before the wild weeds starts to grow. Don't wait too long because otherwise the wild weeds would compete with your grass seedlings for nutrients. Again use a screwdrivers or the back of the hammer to pull any growing wild weeds. Put grass seeds on those bald spots where the wild weeds had been pulled out. Doing this several times during the growing season will ensure that the wild weeds are removed completely and the remaining are the beautiful lush green grass lawn.