If it is alot of dead suface clippings and/ or thatch it could interfere with the seed making contact with the soil. Water and light making it to the seed could also be a problem. When in doubt, do the harder of your options. Rake the clippings up. Not to do so, in my opinion, is the height of laziness.

 

A good aeration will pull up PLUGS not THATCH. No, you should not collect the plugs, they will decompose and micro-organisms that eat small amounts of thatch will be spread out and will eventually reduce the amount of that you have by a little bit. If you dethatch, then you need to rake it up.

 

Any damaged areas of turf that you intend to seed will need to be raked out for proper seed to soil contact. Then aerate, then seed the areas you raked out. Top dress with some peat moss or bagged tops soil


Ah well, some of the Carolina members have said something about topping with a sand.

They will be here and tell you what you need to know specific to your needs.........

 

I saw a golf course guy on tv mixing a certain amount of sand with top soil and compost and using that to top dress before seeding. Haven't tried it, but I found it very interesting.

 

If you have a heavy thatch layer then dethatch first. Be prepared for a truck load of grass when dethatching!
But unless the thatch is really heavy then core aeratiing, seeding, fertilizing and top soil would do the job. And just leave the plugs, they will decompose.