1. Know if your posture makes your breasts look larger today, or not. Do the mirror test. Looking in the mirror sideways, see if you can draw a straight line from your earlobe through your shoulder, hip, knee, to the middle of your ankle. If you can draw this line, your posture will make your breasts look bigger and perkier, as well as making you look slimmer and taller 2. Practice having good posture. This is by far the least expensive and fastest way to make your breasts look bigger. Do the mirror exercise several times a day to correct your posture. It is more important to build "muscle memory" so that you unconsciously and naturally maintain correct posture without fatigue. 3 . Build up your upper pectoral muscles (working out lower pecs will actually decrease your bust size). Increasing the bulk of the muscles beneath your breasts will make them appear firmer and more rounded. Regular push-ups are one way to achieve this; build ...