i am going to redo my yard this spring and am not sure the best way to so it. We have decided in the areas that just don't want to grow grass we are going to landscape. The rest of the yard is just crap though. very bumpy and patches of grass and weeds. We are going to sod it. What should I do to prep it though? Do I need to kill all of the existing stuff, add soil, i am going to aerate it to get rid of some compaction. Any advice would help. Thanks!