If your woman is capable of a breast orgasm, you are definitely going to want to give her one. The only way to find out is to give it a good try and see what happens. If it works, and she did not know it was possible, she'll think you're a god.
The best position set up for maximum stimulation
When most men attempt to do this, they want to lay chest to chest with their woman. This is not the best method for the best sensations, and it will not allow you to use your hands well to begin the foreplay. The best position is to have your lady straddle your hips and have her lower chest into your face. She can prop herself up with her hand and fully extend her arms down to the bed, which will make you pull up your neck, or she can literally lay right on top of you. Either method will work, it really just depends on size differences and how big you both are.
But by hanging down into you, it causes blood to rush to all the nerve endings in her glands and create a much more sensitive area to caress.
The technique that produces the most mind-bending orgasms
If you want your wife to really get an amazing climax, you want to start off with a few minutes of using your fingers to gently glide across the top of the breasts over the nipples, and just barely touching them. Then, you must transition into full mouth play. Most woman will peak by just sucking on the nipples and the surrounding tissue, but some cite that they really enjoy slight nibbling. Use these methods for about 5-10 minutes and you will start to get amazing results.