How to suck good

F20 in my first relationship. Been together 3 years and he seems to love when I do it, but it’s hard to get him to cum from it, it feels like it takes a lot longer than from sex or hand job. I would love to be better at making him cum from it cause he loves getting head but idk how cause he’s the first person I’ve been intimate with and his advice kinda sucks it’s not specific and it’s difficult to understand. I suppose it’s cause he’s also never sucked a dick before so I’m hoping a girly or a boy with good communication in that area could help me out? I want to get better at it for him.