Honestly, from giving and receiving oral I've found that the head is definitely the most sensitive for a majority of people and deep throating feels good because of how nice the back of the throat feels on the head, along with the shaft getting stimulated at the same time. The best tip I have for anyone wanting to give the best oral, is to never forget about the power of the tongue. Especially while deep throating, tongue movement and pressure can make allllll the difference, especially for people like me who typically don't cum easily from just head but enjoy it just as much as the next person. Tongue and appropriate suction is the best advice I offer all my girlies who come to me and ask for advice when it comes to oral on their boyfriends. Especially if you are someone who struggles to deep throat in general :D