Canned pumpkin has its place, no doubts. And if you're seriously lacking freezer space, please stock up on some canned pumpkin during the holiday sales. But if you're purchasing a pumpkin to carve for Halloween, please don't lose out on all that delicious pumpkin meat by just tossing it after the candy binge ends. Most people think salvaging a pumpkin is hard work. It's not. Or I wouldn't do it.
There are only 2 methods I use and I'll let you decide which works for you.
Method #1: Oven Roasting
Cut your pumpkin into chucks -- assuming it's been scooped clean; if it's not scooped clean on the inside, then you'll need to start with that. The chunks should fit into a 9x13 or other sized baking dish. You'll want to add about 1/4-1/2 inch of water to the pan, place the pumpkin pieces in flesh side down, and then roast anywhere from 30 minutes to an hour, depending on the size, how much you put the into the oven, etc. Set the oven at 350* and check on the pumpkin periodically. Once soft (you should be able to stab it easily with a knife) remove from oven and cool. When it's cool enough to handle you should be able to just scoop the flesh out with a spoon. If it's too chunky for your taste, you can either blend it up or use a potato masher on it.
Method #2: Slow Cooker
Again, I'm assuming you've already used your pumpkin as a jack-o-lantern and that it's clean on the inside. Slice your pumpkin into easy-to-handle wedges and remove the flesh from the rind. I like using a smaller knife for the flesh removal -- a paring knife or even a tomato knife if the blade is strong enough to handle it. The flesh can be in chunks ranging in size, though mine are normally around 2 inches in any direction. Dump into your slow cooker, add a small amount of water 1/2 cup depending on how much pumpkin flesh is in the crock, and set to low. I usually check on mine every couple of hours and stab a piece with a knife to see if it's soft. Once soft I turn off the slow cooker, grab my potato masher and start mashing. Some people prefer to use a blender and blend it up smooth. I don't make much pie (just 1 or 2 if needed for a holiday dinner), so it doesn't matter to me if it's a bit chunky. Most of my fresh pumpkin is used for muffins and cookies and I don't mind a chunk or 2.
A Few Notes:
With either method you'll need to freeze your pumpkin in 1 or 2 cup increments. I generally use the slow cooker method because my daughter is 5 and can't carve a pumpkin yet, so she paints it instead. Paint and ovens do not mix. If you have saved your pumpkin seeds, you may want to roast them as the seeds are very healthy. Here's a recipe with some great tips from the reviewers.