Pencil:

Get and use a soft one. 2B. Use a soft touch.
Or try an artist pencil made by Conte - markings from it's water-soluble lead are easily wiped away with a damp cloth.

Use a pencil of this type when dry-hanging commercial-type vinyls, but an ordinary one with the pre-pasted type of papers. Otherwise wet hands, wet paper and wet walls will all see to it that your markings get erased before you need them.

Most straight or drop-match patterns are quite obvious, but some repeats are nearly impossible to find without a bit of studying.

Hold up the free end of the roll and mark your match on the wall. You don't want to be looking for the elusive match from atop a ladder, whilst balancing on one foot and holding and sliding your wet strip around.

Instead, lay up a dry strip for length and find the match against the previous. Draw a light pencil-line across both the last applied strip and your new unwetted one. Make this mark fairly high on the wall. Then when you dunk and climb and fling, it will be right there, saving you from a needless second search.

Erase your markings as you go along. A wet sponge may do it. Otherwise, go back later with a soft clean eraser.