I would hire someone if significant grading is required.

We have a 15x30, and the install took a long day with 3 guys.

This included a lot of grading beyond what the landscapers had done. The fact that he had a small dozer on hand and a dump truck on call for dirt if necessary (which I paid the dump truck driver directly for) are the kind of things that would be hard yourself. It is amazling how a dump truck full of dirt spread out over a 15x30 area becomes ... only a few inches.

They used a spinning laser level (like drywall contractors do) to check the levelness around the whole pool. I'm pretty anal about such things, and I was impressed.

After watching them, I realized I could do this myself, but the extra time and frustration, especially since grading was necessary, made me happy I did not.

If I had a round pool and a flat backyard with easy access, I'd probably do it myself. But I have neither ...