Save what is on the screen now, so it is there when the signal is not. Do this before you leave the road.
Tiles come from OpenStreetMap and OpenTopoMap volunteers. Save the area you need and no more — it is a courtesy to the people paying for those servers.
Bring in your own published sheet — a quadrangle, a survey map, a mine plan, even a photograph of a paper map — and pin it to the ground so your position sits on it.
Tap a place on your sheet you can identify — a summit, a road junction, a corner tick — then give me its coordinates. Two points is enough for a north-up sheet; three or more also corrects rotation and the skew of a photograph.
A GeoTIFF or an image with a world file pins itself with no tapping at all. Anything else — including a photograph of a paper map — you pin by hand, and it is quick.
Map what you see. Contacts, faults, float trains, the edge of a landslide.
Tap the map to read the geological unit under your finger. Tap and hold to move the crosshair without panning.