My experience with vintage frames, I currents have a few hundred...
Goo gone works best for head tape residue
Alchohol seems to work best for scuffs
A toothbrush and alchohol or even soapy water work great for getting in and around the grommets to get the dirt out. If you want to clean the frame while strung you need to get a bottle brush or a gun barrel cleaning brush (plastic brissled not brass).
Careful with stuff like goof of because it can remove the clear coat on some frames. Especially if your rubbing hard.
If you have a frame with a rubberized coating ala prince warrior, gamma 9.0 etc you need to be really careful what you use and even how you store the racquets as the ruberized coating does not hold up over time and gets sticky and messy.
You can also use painters tape for head guard protection. It does not leave a residue and does a good job of protecting the frame if you put a couple layer on. Its also easy to find and reativly cheap. The colors kind of stink though for some frames.
Painters tape might be a viable option for some though as I have seen head guard tape pull paint off vintage frames pretty regularly. Its not a huge deal to me as I tend to play with my frames but if someone has a rather mint vintage racquet and just has to git it a light hit painters tape might be worth a try.