One of the things you can do to increase the power of your characters is enhance their weapons and armors at the Smithy, which is unlock pretty early in the game on Outlander Lane. As you complete the Shop Quests for the Smithy, you will be able to increase the levels of their equipment by using resources and some baqua. In order to get this trophy/achievement, you will be required to get CJ’s weapon and armor up to +30, which is the maximum. Note that +20 is the max you can go during the main story, so you will need to be in the postgame in order to get the final quest from him to get to +30. This can be a little bit of a grind, as you will need a lot of resources, so you may be required to farm some here and there.