How can I decorate a wall that is 12 ft long and it not look messy?

Start out with a center piece, perhaps a mirror or large picture, then work your way around that, some floating shelves staggered on each side, maybe some sconces beside the mirror, or you could just try one of those pictures that come in 3 canvas panels.

Larger wall hangings always look less cluttered than many little things scattered over the wall. Hanging things in groupings also works. Use odd numbers rather than even - like 3 pictures - is more interesting. Keep it balanced.

As an example: I have a 8 foot wall in my eating area. It has a large 30 X 42 inch mirror in the middle to reflect light and the window on the opposite side. On one side I have a wood carving that's about 20 by 32 inches high. On the other, I have a grouping of 4 items that together make a rectangle equal in size to about the same as the wood carving for balance.

Shiplap. Then ad color to adjoining walls for that Pop!

Depends where the wall is inyour home, living room? bedroom,? kitchen? outside? Depends on your tastes in art, colors, interests. Depends on your money for: paint? decoration article? paintings? wood finishes?shelves with treasured articles? No info, no ideas. Send more news or pics.

I have been seeing some really neat murals that say they are easy to install. Do a google search and see what comes up.