Type selection.
WHAT MATTERS MOST
Legibility at the sizes you actually use.
WHAT TO CHECK
How it reads at small sizes Whether numbers are distinguishable Whether similar characters can be told apart Whether it has the weights you need
THAT THIRD POINT
Some typefaces make capital I, lowercase l and the digit one nearly identical.
That causes real errors in references and codes.
HOW MANY TYPEFACES
One, usually. Two at most.
WHY
More produces inconsistency without benefit.
WHAT TO VARY INSTEAD
Size and weight within one family.
WHAT TO CONSIDER
Loading cost. Each weight is a download.
WHAT TO LIMIT
The number of weights to those you use.
WHAT TO ALWAYS SPECIFY
A fallback, so text displays if the font fails.
WHAT TO CHECK
That the fallback does not shift the layout dramatically.
WHAT TO TEST
On a phone, at actual size, with real content.
