When translating things professionally I use the standards of the target language. Informally, though... screw it, I use my own punctuation conventions across multiple languages:
- instead of en dash, tilde for ranges; e.g. 19:00~22:00.
- no em dash either - I use space, hyphen, space.
- generally I avoid single quotation marks, by default I use double.
- nested marks become guillemets; e.g. "she said «fuck this shit» and left"
- nested parentheses become square brackets; e.g. "I'm not buying cheese (although I love it [specially gorgonzola and emmenthaler]). Except if I'm writing about phonetics/phonology, then I simply rephrase the sentence.
- I use the semicolon a fair bit; perhaps even more than the comma.