Glasses with nose pads can be adjusted to give you a perfect, custom fit. If they sit too high or too low, do the following:
The correct temple arm length will make for a more comfortable fit and will prevent glasses from sliding. Note: when adjusting your temple arms, be sure you do not place any stress on the hinges.
Place your glasses on a flat surface to ensure level alignment. Both temples should touch the surface on the same plane. Flip the glasses on their backside to verify the frame is also level.