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
- 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.
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)