Contrast is an instruction to the eye: look here. Before choosing it, make sure the place you are pointing is the place you want people to look.
Circle the lines you would emphasize
On a photograph, trace the window surrounds, corner boards, fascia, garage door, and entry. Imagine every one of those lines in a strong contrasting colour. The effect can be composed and clear, or surprisingly busy.
Matching trim can let a complicated facade read as fewer larger shapes. That does not require every surface to be identical. A related tone or a change in texture can preserve definition without a high-contrast outline.
Put real materials beside each other
James Hardie’s architectural collection examples show both colour contrast and same-colour texture combinations. Treat the images as a starting point; compare the actual products you can obtain for this house.
Take samples outside beside the brick, roofing, window frames, and other finishes that will stay. View them in sun and shade. Two products with similar colour names can differ in sheen and undertone enough to look accidental when placed together.
Keep one focal point stronger than the rest
Our design preference is to decide on the main emphasis first, often the entrance or a clear window rhythm. Then let the surrounding trim support it. Confirm coating compatibility and manufacturer colour restrictions before repainting existing materials. A calmer palette should be a design decision, not the result of discovering the preferred paint cannot go on the substrate.