Varieties of Sexual Arousal
There are different ways to sexually stimulate yourself. Your penis of course is your primary sexual organ. But in one study more than half of the men reported some sexual satisfaction from stimulation of their nipples. And perhaps those other men just have not found a good way to stimulate their nipples.
Another very classic sexual stimulation is your lips.
Does it Matter?
Probably. This website assumes that, for training purposes, it does not matter whether your sexual pleasure comes from masturbating, ejaculation, or touching other erogenous zones like your nipples or lips.
This probably isn't true. There are different ways of stimulating your nipple. And nipple stimulation probably can lead to different feelings.
Is the top lip the same as the bottom lip? Does stimulation of oral areas lead to the same feelings as stimulation of the penis?
Some day we will know more about erogenous zones and how they make us feel. Until then, you can ignore this issue, or you can explore. Other than that, there are no practical suggestions for now except to enjoy yourself when you sexually stimulate yourself.