Or are you talking about decoration? That I have a huge pile of framed art prints and they go up everywhere. If I was starting from scratch I'd probably keep it minimal and just use bright colours to break up large spaces.
I have classical art and design background. So, about 35 years of training in colour and composition.
But there's lots of rules of thumb out there about lighting and wall colours and where each should be what and why.
Good luck.