So, what to do with a blank white wall..?
Step 1: Image and Supplies
First, find an image that will translate well when enlarged and plastered (this project scaled up a 8x11 sheet of paper to about a 5 foot tall image). Generally something that can be silk-screened makes for a good wall "installation" (blatant art term use). You should be able to Photoshop select photos into a usable format by essentially making it look like a Warhol (blatant name drop), then converting to black and white. I chose an icon from a bygone era in one color. I suppose you could overlay vinyl in several colors, but that is beyond me. Also, really any image would work with this concept, the determinants being 1) vinyl and 2) your ability to use an x-acto knife.
Step 2: Enlarge Image
I did the next step and the editing details in Microsoft Paint, which is a very basic, rudimentary and software version of crayons. Since this arguably worked using Paint, I'm positive you can achieve much better results using a more advanced software program. I copied this into Paint, tweaked and colored it as necessary then saved it as a PDF.
Then I opened it in Adobe and in the print settings, enlarged it to something like 800%. In print preview, I printed only the pages with color on them, so I could avoid printing all 70 pages of the enlarged document. Because I hate puzzles (artificially broken images that for some reason we pay to fix), I labeled the pages as they came out of the printer so I could lay them out later without giving the nose an eyelash.