The methodology that I have used for the Cave Script Translation Project is based on the hypothesis that anatomically modern humans were also behaviourally modern. My approach has been to assume that they were capable of doing anything that we can do, and to translate their scripts accordingly.
My choice of material for translation is not restricted to a narrow period of time or to any one geographical region. If the material resembles Cave Script, and the accepted view is that it is not writing, or that it will never be translated, then I will try to decipher the script.
The translation work is based on pattern recognition. I look at the symbol to be deciphered, and then try to match the symbol against one of my keys. The keys come from Chinese reference works.
Lastly, because most of the subject matter refers to disciplines in which I have no expertise, I check my translations for accuracy against expert websites.