Austen makes free use of her characters' individual thoughts and opinions to show us not only what they think of themselves and others, but what she herself thinks of them. She does a brilliant job of allowing characters to emerge out of their own minds – that is to say, we learn about them from themselves. Elinor, for example, is rather casually described to us early in the novel, but we mostly get to know her from her own thoughts and observations, which tell us more about her personality than any amount of description could.
Austen's dialogue is famously amazing and dead-on. She manages to capture a multitude of different voices in print, and we can distinguish between her characters easily by keeping track of their various conversational styles and tics. From Charlotte Palmer's constant, almost inane laughter to Colonel Brandon's measured tones, all of her characters are defined and re-defined over and over again from their modes of speech. Also notable is certain characters' choices not to speak at times. Marianne, for example, overtly snubs people at times by refusing to engage in conversation (or simply leaving the room), demonstrating her feelings towards them through her reticence. Her expressive personality is crystal clear through her spoken words, or through her silence; Marianne rather dramatically tries to express precisely what she feels at all times, which she communicates quite well, even when it's not entirely appropriate.
Not all of the names are descriptive here, but there are a few that stand out – most notably, the contrast between the organic-sounding Dashwoods, and hard, cold, tough-as-nails Lucy Steele. Steele, of course, is an ideal match for the similarly cold Ferrars clan… after all (and we might be stretching it a bit here), "fer" is French for "iron," which is then made into steel.