Fellatio is mouth on penis. Lips cover teeth. A hand on the shaft covers what the mouth does not. The receiving partner can keep a habit of thrusting out of the other person’s airway by actually listening when they choke or tap.

Depth is optional. Most of the nerve interest sits in the head and the first part of the shaft. A rhythm that stays predictable beats an attempt to impress. Spit is lube until it is not; add the bottled kind if things drag.

Barriers exist. Flavored condoms are less romantic and more reusable as a policy when tests are not current. A cold sore belongs nowhere near this act.

Ejaculation in the mouth is a separate yes. Assume no until you hear yes. Then have a towel, because manners still apply.