1. Always plant them in a group of three. They are one of the plants that grow best in a group, which is called ‘a mound’. It’s not a mound of earth, not a little hill, but it’s the name for a little group of a few pumpkin plants.
2. They love growing with beans, so if you can, plant a pumpkin (at this point, get a little guy already started in a pot, not from seed, to make sure you have enough time to get ripe pumpkins)… and then plant a few bean seeds nearby.
3. They are VERY hungry, so make sure you give them plenty of organic fertilizer. Just buy a bag of Dr Earth brand organic vegetables fertilizer, or similar.
And as with everything, water at night, about 2 hours before sunset is ideal, but it can be any time in the evening also if you’re out. Better than watering in the day.
As for the slimy ones, like slugs and snails, spray is pointless. The best way to deal with them is simply to pick them off by hand, one by one, and either destroy them (squishing underfoot etc) or throwing them far, far away into a park etc.
There are various other methods (beer trap in the ground, copper tape around the plants), but all of them are crap compared with simply removing them by hand.
Other than that, pumpkins are pretty easy. It’s too late to sow seeds and have guaranteed ripe pumpkins in time for Hallowe’en, but pick up some organic baby plants from the nursery, and you’re good to go.