Put a space before units of measurement, eg 6 mg. Use 6 litres or 6 L to avoid lower-case l being read as number 1. Big numbers take comma only after five figures, eg 4000 but 55,000. Adjust wording so that no sentence begins with a numeral. Section 4, not Section Four.
Single quotes are for unusual uses or new words .
Capitals Minimise use of capital letters. Give trade-name drugs a capital letter, eg Valium. Do not capitalise generic drug names, eg diazepam. In titles etc, no capitals after a hyphen, eg Task-based Learning. Capitalise specific names only, eg Professor Smith, but he is a professor.