Pictures would sure help to understand what you are dealing with. How many acres are you trying to smooth out?
Not knowing the type of soil or grass that you are dealing with, there are two ways to go about making dirt smooth. One is along the lines you've already tried. Tear up the ground and then smooth it out. Depending on your grass or ground cover/soil, this might be quite challenging. Even with heavy equipment, the degree of how hard the surface is, will decide on how big that equipment needs to be. I've had some success with running a disk over the ground first, but in some areas, that hasn't worked either. I have a dozer, and it works good on some areas, but not in every area. If it's just sort of rough, then it's almost impossible to make it nice with the dozer. I need to really tear it up first in order to have enough material to work with.
The other way is to add material and smooth it out. For small areas, this is by far easiest way to go. Getting that material is the only challenge. If you have a way to move it, and a source of getting it, then you are all set. If not, then having a dump truck bring it in can get expensive, but it might be the best option. Spreading it and smoothing it with my loader bucket works the best for me. Then after I'm done, I pull my drag around with my small tractor. The drag makes it all nice and pretty. It moves around a little dirt, but not enough to change anything other then fine tuning. It's awesome for taking out bumps and filling in small holes.
Good luck,
Eddie