Wear a nursing bra or tank -- they have clever flaps and latches you can open with one hand. You can also throw a cute cardi or button-down blouse over a regular top to keep your middle covered when you lift your shirt to nurse.
Practice nursing in front of a mirror, both seated and standing (many fussy babies will latch only if Mom is on her feet). You'll get an idea of what passersby will see and can make tweaks if you're giving a peep show.
Does she turn her head from side to side or put her hand to her mouth? She probably has the munchies. You'll want to nurse before her crying spirals. If you wait until she's wailing, getting her to latch may be tough.
Find a low-traffic zone, and use your stroller as a barrier to keep people at bay. Once settled, hold Baby in the crook of your arm and bring her close to you, then undo your nursing top and bra, or pull up your shirt.
Hold Baby's head close to you so she's blocking your breast, then fasten your bra and pull your shirt down. Switching breasts? Position your shirt as if you're closing up shop, reposition Baby, and start feeding.
Most states, along with the District of Columbia, have laws that specifically allow women to breastfeed in any location. Learn your rights at NCSL.org.