u/BisonUpstairs784

I need advice.. I need to level my lawn, has dips in various areas, but im also worried about how to deal with the grass also.. was thinking of completely starting overs by Tilling the ground, bringing loads of dirt.. than installing SOD. But was being told I don't have to Till.. just install the dirt, killing the old grass and installing the SOD to overlay it.. curious what everyone thinks.. maybe a different method? Thanks for any type of feedback!