If your display glass is badly cracked, tape over the glass to contain stray glass and make prying easier.

Heat an iOpener and apply it to the left edge of the display for at least two minutes.

You may need to reheat and reapply the iOpener several times to get the phone warm enough. Follow the iOpener instructions to avoid overheating.

As you're waiting for the adhesive to soften, move on and read the following step to get an idea of where to pry.