With a wide gusset, the side pieces won't need to be so high. If you have a narrow gusset, you'll need high side pieces to compensate. Steiff bears tend to have wide gussets, a Pooh bear would have a narrow one. And make the gusset a bit longer than you'll need. You can always cut it off later and the extra length may save aggravation.
Long noses are cute, but most be balanced by equally long heads.
The curve from the nose to the neck is also very important. Too shallow and your bear will resemble a weasel. A teddy bear is an art form, and follows certain rules like every other art form. Perhaps the most important of those rules is balance. In a photograph, for instance, we center the subject, or we put him off to one side and balance the other side with another part of the background or object.