I pinned the front and sewed it on alone so that I could make sure the writing was straight and centered. Then I folded the edges of the back piece down and sewed in the groove to attach it on after.
It thought about adding grommets, or ribbons on the back for hanging it, but I decided not to add anything at all for attaching as I will probably be safety pinning it to my tablecloth.
The scraps I used (I cut up an old curtain liner) just happen to be almost the same colour as the paint on the wooden sign so I will be comfortable using both together or alternating them out depending on the situation. Cost for sign #2: also $0.00 - it's built of leftovers.
Do any of you do craft shows or have a market stall? I'm wondering how other people display their brand. Feel free to leave a link in the comments if you have one you would like to share.