At level 1 until 5 or so just killing random stuff outside of town is enough, then you can start focusing on your hunting log. While people here have talked about FATEs, it can sometimes be hard if too few people are around, so you have to pick FATEs that are multiple smaller mobs rather than 1 large boss mob. Once you get the 15 you can dungeon grind. It takes time sure, but it helps you learn your job better.