RLCraft Skill Question

Brand new to RLCraft, currently playing Dregora because I heard it's harder, and I prefer the challenge. How do you gain skill points? Is it based on XP earned, the number of mobs killed, or something else? I've just been running around doing stuff and earning them. It might be on the wiki, but I’m blind and probably missed it. Also, what’s your preferred method for earning Skill Points?