I let my arm rest for the two days it took for Amazon to deliver the Goo Gone. I spread it on with a paper towel, and let it sit for a short period. Then I took a cleaning rag and careful removed the rest of the residue. Easy! Next day I removed another decal. I applied the Goo Gone to the thick adhesive residue, and let it sit.
https://www.amazon.com/Goo-Gone-Original-Liquid-Adhesive/dp/B00006IBNJ

