Get some oil - olive is fine and place the bottle in hot water for some minutes to warm. Then using the oil massage your breasts circular motions work well. For maximal pleasure avoid the nipples as long as you can stand to. Allow your fingers to stroke right up besides them and play extensively with the areolas but the actual nipples you are teasing allowing only the slightest brushing contact as yu rub near then.
Your nipples will become increasing desperate for sexual attention - they will become very erect and when you finally begin touching them it will feel much better then normal, Uses different stimulation pinching tugging, twisting, pulling, etc.
Other times try stimulating your breasts and nipples with a feather duster, a silk scarf, ice cubes, you use an electric tooth brush and some oil on your nipples (make sure all traces of tooth paste are removed because it stings and burns on sensitive tissues like nipples)