I love to add interest in an interior with beautiful wallpaper and my number one rule is; patterns don’t have to match.
One of the best ways to mix patterns with wallpaper is using colours from a similar palette. They do not have to be made up if the same colour, there just has to be some link between each colour in each pattern.
Keeping in mind scale and size is also important. Using multiple patterns with all the same scale is a big no-no. Try introducing some larger scaled patterns, with some tighter scale, mixing both organic shapes with geometric. It is also good to introduce some block colour to give the space ‘room to breathe’.
With patterned wallpapers, try introducing another pattern with floor coverings, such a patterned rug or mosaic tile. Or layering a patterned bedhead over a patterned wallpaper. Or even try layering a piece of furniture with a pattern over a patterned wallpaper.