If your toting a gunlance around you need to be considering artillery and guard + over most every other skill. Artillery will increase the damage for your shells and guard + (not guard up) will reduce the stamina drain, chip damage, and recovery animation from blocking for each level of it you have. So far I haven't seen a full set with both so your gonna have to mix a set with gems/charms.
Why guard + over evasion? Gunlance has a standing attack that puts you into a blocking state almost immediately. Another reason is that during any animation if you shell you will be able to go into blocking position faster. For giggles you can use these two tactics with the auto block charm and for the few times you misread an attack it will block for you.
Why artillery + ? You should be shelling, often. The boost will allow wyvern shot and the full shell unload attacks to consistently flinch, knock down, and break monster parts. Shelling will prevent bouncing and if you increase the shell damage even the little ones will break gaan's chin without much effort.