Acetone, paint thinners or easier to get nail varnish remover. Just watch as these products may take any polish off as well and leave a dull patch not always just might but a quick spot of polish and sorted.
Just car wax for me, and elbow grease, works on tar spots etc. But it probably depends on the glue and whether its a type that has harden or remains flexible like contact adhesive.
petrol also very good at glue removal just done a large area on mine where decals had faded and looked awful, petrol on a cloth soon got rid of it then a quick polish after.
Peter.