You should not use more than 3 fonts (size/color combinations). Text sizes should be set using SP units. They are fairly consistent between different devices (scale-independent) and take in consideration user settings. Text sizes such as large header (H1), sub-header (H2), and default should be set for each device combination (see above for explanation):
✓ small - mostly ignored
✓ normal-mdpi
✓ normal-hdpi
✓ large
✓ xlarge
