How Do You Avoid Hernias??
Well, I think the tendency might be more prevalent in those who carry most of their weight in their stomachs. Just a factor that there is more pressure on the incision line is one reason. That, and some people are just going to be prone to them.
Some things you can do: Wear your binder religiously. Keep it snug and be careful not to do too much for awhile. Don't be lifting heavy items and don't exert yourself too much while recuperating. I have heard that you don't want to do sit ups or crunches for the first year or two after an open surgery as well. Probably again, depends on the person.
As far as what to do in advance to help, well, I suspect doing abdominal exercises can only help. The stronger those muscles are the better off you will be post-op.
Good luck - hope that helps!
(For what it's worth, I am normally hourglass shaped but at my heaviest was quite big in the gut. I did fine and do not have a hernia...)
Dina