Stickers have left residue on some windows and old glass jars. I have typically used acetone to clean the residue but is there a better / easier way?
There are extremely effective window scraping devices, which ensure that you always maintain the correct blade angle and dont scratch the glass pane.
also you can spray some simple window cleaner onto the glass while scraping.
Use a new razor blade on the windows to scrape it off (blades like the kind you use in a extractable utility knife). Angle the blade at about 30 degrees up from laying flat against the glass and move in a scraping (rather than slicing) motion - works great with paint too. The old glass jars will be more difficult because of their shape... I'd try putting them in a dish washer or possibly using Sherwin Williams 'Oops' product - Lowes sells the same thing labeled as 'Goof-Off'. You might also use the 'Oops' product to keep your razor blade clean when working on the windows.
Goof-off works wonders and won't cause any discoloration with the glass. Try to breathe as little of the vapors as you can as the smell is pretty potent.
WD-40 works well if used with caution. Be careful of overspray or spray on a paper towel or fine steelwool and wipe on the glass. Then use regular glass cleaner to remove the WD-40.
Magic sponge and elbow grease has worked wonders on set-on sealant overspray on house windows.