I always use the pre-cut holes to align it, then use a couple buttons to clamp it down, and a clamp on the side with no buttons (with a cloth, so the clamp doesn't mark the overlay!), Then what you do is peel the top section (about an inch), and stick it down.
By now you can check your button holes again and especially the alignment with either side, near the bottom. If you are, then you're good to go. Remove the clamping buttons, and just start slowly pulling the peel off across the whole width, about a half inch at a time, while firmly pressing down the exposed adhesive section section. Each time I'm making sure the overlay is firmly sticking and all air bubbles are squeezed out towards the bottom.
No soapy water necessary.