Make some small mounds about 10 inches across and 6 inches deep, then plant the pumpkin seeds 3 to a hill, a few inches away from each other 2-3 inches deep. The mounds should be about a foot apart. Cantaloupe seeds should be planted in the same way. Watermelons, too. I let mine take over about 1/2 of the yard because they love to spread out. You'll get the most pumpkins that way, and don't have to cut as much grass, either.
With all this global warming, I had to wait until June to get mine in so they wouldn't freeze.