Not mine but so fairly good general tips. I think you can distill it down even more:
  • Be careful when mixing fonts that are different 
  • Less is more – stay consistent with mood, time, design (be appropriate to your content)
  • Make it readable

 DO:
  • Know your font families
  • Combine a Sans-serif with a serif font
  • Combine a serif with a sans-serif font
  • Contrast is the key.
  • Stick to 2 fonts.
  • Combine fonts of complimentary moods and time eras.
  • Use different weights of fonts only in the same family.

DO NOT:

Combining 2 similar fonts is not cool.
Don’t mix moods.
Avoid: Comic Sans, Papyrus, Curlz, Viner, Kristen, Symbol (well, at least you need for scientific or mathematical writing)