A person becomes a saint by wanting to be better and loving God. You don’t have to be perfect (no saint was). You don’t have to have a perfect past (some saints only turned to God at the last moment of their lives, like Dismas the guilty thief in Luke 23:40-43). You just need to pray for it, fast, love your neighbor, and be willing to put aside everything that separates you from enjoying happiness with God now and in the next life. It’s really quite simple. I just really wish that simple meant easy.