Choose the things you will live with.
A finish is easier to judge when you can see it in the room, beside the materials it meets, and in the light it will receive.
Compare materials side by side.
A small sample can be useful, but it rarely tells the whole story. Scale, edge detail, lighting and the adjacent surface all affect how a material feels in a finished room.
Stone
Look at its variation, texture, edges and the way separate pieces meet. Consider where it will be touched, walked on or exposed to weather, and discuss suitable finishes and care with the supplier.
Timber
Species, grain, cut and finish can give the same element a different character. Bring larger samples into the actual light and compare them alongside flooring, fabrics and painted surfaces.
Metal and glazing
A slim frame, a deep reveal or a well-placed handle can make an opening feel precise. Think about reflections, shadow, touch and maintenance alongside the appearance in a drawing.
Understand how a material will age
Some surfaces will develop a patina; others need more regular attention to keep their intended finish. Understand that difference before making the choice, especially outdoors or in busy family rooms.