Breasts can be fun to play with, both for the person playing and the person who has the breasts. Some people can even have orgasms from breast play alone. Others need breast play combined with genital stimulation.
How to Touch BREASTS 101 [Airplane Edition] | Adina Rivers
Here's your field guide to the chest.
As with any other sexual act, consent is important when it comes to breast play. Keep in mind that some people may not want their breasts played with. For some, it’s a matter of personal preference; for others, it’s a matter of gender identity. Trans and genderqueer people may not want their breasts touched.
You can and should tell your partner directly what they are comfortable with, or you can start slowly by moving your hand over their shoulders and collarbones. If they tense up or pull your hand away, move on to other parts of their body.