Remember to save in PNG format for the best results!
Google's design practices have proven both successful and influential, and a guide to the principles is available for free. Check out their Material Design site for ideas, pointers, and best practices.
MinerBytes can handle PDFs, but they don't like it. The Raspberry Pi processors that power the signs are a tradeoff between performance and affordability, so the way they display PDFs can be unsatisfactory. They handle PNGs just fine, though!
If you have a PDF, you can make it more MinerBytes friendly in just three steps:
And you're done!