Lift and remove the back cover.

During reassembly:

This is a good point to power on your phone and test all functions before sealing it up. Be sure to power your phone back down completely before you continue working.

Remove any adhesive chunks with a pair of tweezers or your fingers. Apply heat and isopropyl alcohol (90% or greater) if you're having trouble removing the adhesive.

If you're using custom-cut adhesives, follow this guide.

If you're using double-sided tape, follow this guide.