Remember to switch the home button from your old display to the new display (in most cases, this is not provided). The home button gasket is thin rubber, so care must be taken not to tear it. Also, check that the mesh for the speaker hole is present in the replacement; if not, move it over from the old display.
Be sure to peel off the protective backing (usually blue or pink) from the new panel before installing it.
If your replacement display does not come with a 7 mm clear plastic ring surrounding the front-facing camera, be sure to transfer it between the old and new display.