Evasion skills in your armor really shine as they help improve your poor mobility. Guard Inc. can also help improve your shield. Due to the long unsheathing and sheathing animations and the fact that bowguns do not have an unsheathe attack, you should pull this weapon out in advance. Use your rolls when you need a burst of speed or to just get out of the way. You should always remember to keep a "bubble" around your target where you don't go in: generally a roll or two away from the wyvern depending on the shot type you are using. You should try to bring materials to create more ammo as you will likely run out if you are going to be using one particular type of shot.