Choose roles before fonts
List what your typography needs to do: a headline that sets the tone, body text that is comfortable to read, and small labels that help people navigate. You can often cover these roles with a single family and a few weights.
Make contrast deliberate
A large expressive heading works best when the surrounding text is calm. Contrast can come from size, weight or style. Avoid changing all three at once without a reason. Repetition makes a page feel coherent.
Space is part of the type
Read a paragraph at the size it will actually appear. Adjust line length and line spacing together. Keep a heading close enough to its paragraph that they read as one thought, then add more space before the next thought.
Check the awkward cases
Try a long title, a small screen and a missing web font. Check labels inside buttons and the longest navigation item. A type system is ready when the ordinary and awkward examples both remain readable.
