A big factor of this game is preparation and not rushing into doing everything without working to get the appropriate tools, food and gear. The only trouble I've had with a boss is the last one - that's crap for me, I never seem to be able to hit that in the right way. Other than that, they are fairly simple to figure out. On the plus side, you don't NEED to do the bosses if you don't want to. The only one you particularly need to down is Modor so you can build the artisan table.