The Internet is also a great place, but it may take you a long time to find the right picture/s.
Using the internet also means that any picture you copy needs to be the type that can be enlarged later, you will often find that after downloading a picture into your software, when you attempt to enlarge it, it will become distorted. But don't lose heart there are plenty of sites which have clip art that is ideal for less detailed murals.

Magazines and comics are also a good place to look for design ideas, in fact any type of literature, when you know what genre you are looking for, most should prove helpful.

Stencils also provide a good source of inspiration, but these can really only be used if your design is abstract. If you cannot find a stencil you like most good DIY shops stock the paper and tools needed to make your own stencil, this however can be tricky and takes a steady hand. Or alternitavely check out our new Make A Mural Stencil range which has been designed to be used to make your very own unique mural.