Nipple Play and Breast Orgasms
The nipples have over 800 nerve endings. Ancient texts encourage men to suck on women’s nipples, because doing so causes women’s bodies and minds to relax. Science has also shown that nipple stimulation releases oxytocin, the relaxing, bonding, and love chemical.
According to a recent study, researchers discovered that stimulation of the nipple activated an area of the brain known as the genital sensory cortex. This is the same brain area activated by stimulation of the cervix, clitoris, and vagina. What this means is that a woman’s brain seems to process nipple and genital stimulation in the same way. 
Some partners are into certain kinks and fetishes and it's probably best to experience your first nipple orgasm with someone who's into breasts and nipples. Allow space for the orgasm to happen and let go of inhibitions. Tensing up or forcing something to happen is counterproductive. 
Know the different ways to stimulate her breasts. Aside from your hands and fingers, you can use your lips, teeth, and even your facial hair. Each type of stimulation creates a novel sensation for her which can register different levels of pleasure. Don’t be afraid to experiment! 
Start playing with her boobs with her clothes on. Foreplay usually starts with your clothes on and you would definitely agree that groping over her bra and sweater is definitely hot. While she doesn’t feel skin to skin contact yet, the anticipation that builds as you stroke the areas where her nipple should be provides the thrilling sensation that would turn her on. 
Use the tip of your fingertips to lightly trace lines over the skin of her breasts all the way to areola and nipples making your touch lighter as you reach the center. Seeing goose bumps over her skin? Then you’re doing it right. 
Use the palm of your hand to rub her chest. Using both palms fingers facing outward; rub her from her stomach all the way up to the base of her breasts. Then trace the outline of her breasts with your fingers in a circular motion until you end up in her collarbone. 
Pulling. Rest your hands on the cup of her breasts while leaving your thumb and index finger free to play with her nipples. Starting from the base of her nipple, draw her nipple out in a pulling motion applying decreasing pressure as you let it slip from your fingers. Don’t overdo it or you end up hurting her. 
Kissing. A kiss on her breast registers the sensation of soft, warm, and slightly moist lips that she’ll be sure to love. Start with short pecks from her underboob and work your way with longer and deeper kisses until you reach her nipples. Note that you need to maintain a pattern while doing this. Kissing her breasts in random places would make her feel ticklish. 
Have your partner trace the ice cube over your nipples while they kiss your neck. Once your nipples are nice and cold, have your partner warm them up with their mouth and hands. 
More advanced nipple play techniques can be found here.
Other Breast Topics
Nipple Play/Orgasms - breast-focused foreplay techniques.
- Confident Lovers: 3 Things You Don’t Know About Nipple Orgasms https://www.confidentlovers.com/nipple-orgasms
- Oxytocin https://en.wikipedia.org/wiki/Oxytocin
- Women's clitoris, vagina, and cervix mapped on the sensory cortex: fMRI evidence. https://www.ncbi.nlm.nih.gov/pubmed/21797981
- Thrillist: How to Have a Nipple Orgasm https://www.thrillist.com/sex-dating/nation/how-to-have-a-nipple-orgasm
- Love Panky: Nipple Play: How to Pleasure a Girl by Focusing on Her Breasts http://www.lovepanky.com/men/understanding-women/nipple-play-breasts
- FabFitFun: 5 Ways to Heat up Your Sex Life Using Ice https://fabfitfun.com/magazine/ice-sex-tips