1. Invest in a tailors measuring tape and use instructions with three nursing bra measurements and not just two fro a better fit.
2. Measure for and order your nursing bras 3-4 weeks before delivery. You will already have grown to the largest cup size you will be other than the few days of engorgement. This will allow for any back orders or delay for specialty sizes.
3. Don't just order one bra. You never go into a dressing room with just one swimsuit to try on and have success. Bras are not any different. Check that the nursing bra return policy is 30 days and try a few styles or sizes to get the best fit. Bras are usually only about $3 each to return by mail and a great fit is well worth the extra cost.
4. Take advantage of a nursing bra sale to like the 4th of July sale shown below to try new styles, but don't try an underwire until you are at least 8 weeks postpartum and have had no difficulty with plugged milk ducts.