You can't and you don't. You can't buff it offensively without purple quality DOffs which most players don't have at that level, and you can only do so much with the lack thereof of tac consoles and BOff abilities that the freebie ship suffers from. For that matter, all Galaxies absolutely blow when it comes to tactical capability. There are much better ships out there tbh.

As for the maneuverability? EM, EPtE (do NOT recommend), deuterium surplus, and Aux to dampeners are your best bets. But I would recommend against using the galaxy to begin with, and would discourage you from getting any of the c-store variants.