Don't ever forget than seam allowance. I know people who don't figure it into the pattern, but I always do. Saves me mistakes later. Starting with the body, think about whether you want a fat or thin bear, male or female. Jot those things down too, and use them as you start to shape the body.
Curves are always better than sharp edges.
Gently slope into the tummy and back out. The back hump can be a bit steeper. Remember, with your four piece body you have a much better chance of getting a fat bear. I have found that when I try to make a fat tummy, I overdo it a bit and have to trim. I also have to be careful to slope down enough in front from the neckline so the bear's head won't end up sticking nose up into the air.