I started painting around the stem at the top. I painted with the tip of the brush right into the edges of the fake stem. Once I got the edges of the stem painted, I spread out down the pumpkin to just below half way down.
After the top half dried, I turned it up and painted down. One thing I really like is that there is very little dripping with the gesso-based chalky paint and the brush strokes don't show. The jar to the right of the pumpkin in the picture below is what I use to mix up the paint.
I buy the glass jars at garage sales, usually for around 10 cents a piece. The plastic lids I buy at Walmart for very little money; I think there are about 8 plastic lids in a box for around $3. I like the plastic lids much better than the metal ones that come with the jars when you buy them new. I use a permanent marker to write the color of paint (e.g. yellow) I used to mix with the gesso and then dot a bit of paint on the lid like they do when you buy paint at the store. I also dot the gesso-paint mixture on the top of the lid too.
It would look something like this: yellow paint (dot of yellow paint) with white gesso - mixture color: chalky off white (dot of mixture)
The great thing about the plastic lid is that you can scrub the permanent marker and the paint dots off the lid with a little effort when the paint mixture is gone. I only re-use them for other paint mixes once I've mixed paint in them.
I like how the lines on the pumpkin really show up with the chalky paint. I'm happy with the results and would rather make my own white pumpkins out of old orange ones than buy them new because I can change the white to make it browner, grayer, bright white...you name it...just by adding a little of that color to the gesso-white paint mixture.