1. A single file should contain fewer than 20000 lines of code. Preferably 1000.
  2. A single file should contain only one class. If this breaks the previous rule then your class is probably too large: refactor.
  3. It would be nice if a single routine could fit into 100 lines of code.
  4. Use consistent formatting. Even better: don’t bother and let clang-format do it. When you change your mind, just update the config and rerun.
  5. Unit testing is awesome and will almost certainly catch on.
  6. Make everything constant: you should be declaring things as constant as a matter of course and then relaxing it as necessary. It’s much easier to reason and test about code when the data are immutable.

References