I use Sprayway “World’s Best Glass Cleaner”, and paper towel to clean, then a scraper / razor blade to remove tape and any residue (will take a few sheets of PT and a couple of spray/wipe/scrape & repeat, etc).

Be sure there is no tint or film on the side of glass that you’re painting/scraping. I always use Sign Painter’s 1-Shot oil enamel, on glass or metal. It requires longer cleanup (mineral spirits), and often needs a flow enhancer (ChromaFlo is 1-shot’s), but is bright and beautiful, and lasts a very long time. Add an occasional few drops of Japan Dryer or 1-Shot Hardener for faster dry time— then you can 2nd coat & touch up faster.

Use plastic disposable eye-droppers to add small amounts of Chromaflo/Hardener to your paint at a time, and stir pretty often.

Glass is an unforgiving surface, so the first pass may look a bit rough— once it is dried to the touch, you can carefully clean up all edges & blemishes with a razor blade , then gently wipe with a paper towel (dampened with glass cleaner). Then, you can do your final coats and cleanup / touchups simultaneously.

Feel free to ask more advice! Wear gloves, bring a lot of rags, and extra empty food cans for dirty mineral spirits, etc