Since so many of you seem to be trying your hand at growing pumpkins this year, I wanted to give you this little golden nugget of information that I found last year when I gave pumpkin growing my first go :)
Check out this site: http://www.pumpkinnook.com/growing.htm
It is FULL of pumpkin growing information. Pay attention to the fertilizers, because that seems to be important. I personally use Blood Meal and Alaska Fish Fertilizer before the vines flower and after they flower I use regular old Mirical Gro. The site strongly suggest an irrigation or some sort of sprinkler system, but I've been watering mine myself EVERYDAY and that seems to be working out fine. Pay attention to the section about covering the vines/pumpkins, especially if you live in a very hot climate.
The pest section is a little frustrating for me, because it mostly references using different pesticides to control the little buggers and I really don't like dealing with harsh chemicals. Last year I had MAJOR problems with cucumber beetles and with vine boarers. With a little research, I found some non pesticide suggestions :http://www.ehow.com/how_7779001_home-remedy-repel-cucumber-beetles.html
As far as the onions, I just chop one up every now and then and sprinkle it around my garden. So far, so good. Also, for the wood ash, I've just been sprinkling it on the plants. Again, so far so good. I'll update as the season goes on, about how these "home remidies" seem to be working.
Hope this is helpful!