Inspect letter construction
Compare the shapes of repeated letters at a readable size. Look at stroke contrast, counters, terminals, and spacing. A typeface's character becomes clearer through these relationships than through a decorative sample word.
Study the paragraph
Set the same short passage in two typefaces with comparable size and line length. Examine word spacing, line breaks, and the texture of the whole block. Reading performance depends on the setting as well as the individual letters.
Check the medium
Paper, ink, screen rendering, and output size influence appearance. Test at the size and medium the reader will actually use. Avoid assuming that an enlarged specimen predicts the behaviour of body text.