You have tried your best, but your art wall still looks terrible. Why can everyone else do it, but not you? Well, it is not as easy as one thinks! Instead of a lengthy lesson, we will just stick to one short tip today.
CHOOSE A HERO PIECE. This is the one that is bigger than the other art work so that you can focus on choosing everything else just to match one piece of art. If they all match one piece, then the rest should all work together. It helps if that piece is bigger than the rest, so that your focal colours and inspiration piece is accentuated in the hero piece of the room.
In this image you can see the owner used the big black, white and yellow modern art work as inspiration. All the other prints and art works have either those colours or a modern painting that reflects the same style.
As easy as that!