Building good typography system makes design much easier and faster. I would like to share with you some tips I use in my projects:

1. Pick a typeface (use one, max 2 fonts)
2. Set base size (usually between 16-18px)
3. Create a type scale (use type-scale.com)
4. Set good line height (1.4-1.5 of font size)
5. Adjust tracking for better readability
6. Define meaningful colors