I chose to do mine all similar so that if displayed all together they'd look like they belonged together.
The background I blogged about recently. It was leftover acrlyic paint from a project my children were doing. Rather than have it go to waste I put it on watercolor paper with a sample credit card from junk mail.
The images were from a Golden Book Dictionary originally published in the 1950s. I bought it for 50 cents at a thrift shop and it smelled like mildew so it was no good for reading. When it is sealed under acrylic gel medium the odor is sealed in and not a problem for one's health (allergies). The illustrator is Richard Scarry. These are cut-out's from the book (not copies).
The letters were rubber stamped (stamp credit: HeroArts) onto yellow cardstock.
I squeezed time in to do this when I woke up on a Saturday before everyone else in the house.
The first series I loved so much I decided to keep it, so I then made a second series.
Note also I kep the paper in the order it was originally. The paper goes four across, then the next ones start left to right again at the second row. For example the vertical red smeal in Sweater can be seen continuing down in the Indian ATC.
The last two were made with scraps of paper left over afterwards, in an abstract style.