An important passage that helps the reader become cognisant of the character of Elizabeth comes just after the famous put down that Darcy says, unfortunately in her hearing, as to why he refuses to dance with her. Note how Elizabeth responds to being told that she is merely "tolerable":
Mr. Darcy walked off; and Elizabeth remained with no very cordial feelings towards him. She told the story however with great spirit among her friends; for she had a lively, playful disposition, that delighted in anything ridiculous.
Here the reader is introduced to two aspects of Elizabeth's character that prove to be crucial in the subsequent pages. Firstly, she is a character who is defined by her prejudice in the same way that Mr. Darcy is defined by his pride. Having heard Mr. Darcy's comment, her mind is made up about his character, and she dismisses him as a proud disagreable individual with no hope of redemption. It is interesting to note that Austen originally planned to call this novel First Impressions, and this title certainly captures the problem that Elizabeth has as she trusts far too much in first impressions, both in the way that she discounts the character of Darcy and trusts the character of Wickham.
Secondly, the quote also establishes the more playful side of Elizabeth in the way that she is able to laugh at Darcy's behaviour. This of course prepares the reader for the ease with which she mocks humorously those around her, both her mother and sisters, but also others such as Mr. Collins and Mr. Darcy. She is a character who is able to laugh at the faults she finds in those around her, even if she is blind to some of the faults that she herself has. These are two of the most important aspects of Lizzie's character as she is presented to the reader in the opening chapters.