How to Initiate a Blow Job for the first time?

So I'm seeing this guy, have been for a few months and the sex is amazing! I am curious though how I go about giving him oral sex for the first time. I'm relatively inexperienced and I don't think he would ever initiate because his goal is always make sure I'm comfortable. I'm scared of trying this and him not liking it... advice on what to do ladieeees please.