I wanted to share this method because I’ve tried many of the available printing-on-wood techniques, including citrus solvent transfer (don’t use acetone, by the way) as well as Liquitex and Mod Podge.
Acrylic Poly Finish (aka “acrylic polyurethane”, “polycrylic”, etc.) is not only cheaper than the above, but you end up with a cleaner image because it is less prone to rub off during the paper-removal stage, it is clearer, and it dries much faster.
As a bonus, you can use the very same acrylic polyurethane to finish the piece. I generally put at least a few coats over the picture.
Here is a video outlining the simple steps.