What are the ways an author has of telling us about a character, and how do we learn about the characters in Sense and Sensibility?
An author can create characterization through either direct or indirect characterization.
With direct characterization, the author comes right out and describes the character, usually in the narrative. We especially see an example of Austen using direct characterization in the opening chapter of Sense and Sensibility. Towards the end of the chapter, Austen devotes a few paragraphs to describing Elinor, Marianne, and even Mrs. Dashwood. She particularly describes Elinor as having "a strength of understanding, and coolness of judgement, which qualified her, though only nineteen, to be the counsellor of her mother" (Ch. 1). From this description, we see that Elinor is definitely the most sensible, most calm and collected character of the story.
An author can also create characterization through indirect characterization. Indirect characterization is when the author "shows" what a character is like rather than "tells" us about the character. An author can relay indirect characterization through the things a character says and how the character speaks. Characterization can also be relayed through a character's thoughts, feelings, and actions. Also, even how other characters respond to the one character in question will tell us about the character. How the character effects other characters, what they think of that character, whether or not other characters like or dislike the character, all help show exactly what the character is like.
Austen's indirect characterization techniques are spread all throughout the book, but it can sometimes help to focus on one particular scene when analyzing characterization. One good scene for analyzing either Marianne's or Elinor's characterizations is the moment when Marianne learns of Edward's secret engagement. For example, we see that Marianne's response upon learning that Elinor has known of Edward's engagement for four months is to be absolutely shocked and bewildered by Elinor's actions. With her own broken heart, she absolutely cannot understand how Elinor could have been "so calm!--so cheerful!" and asks, "How have you been supported?" (Ch. 37). Marianne's initial reaction shows us that, despite their differences in philosophies, Marianne is capable of being influenced by her sister's actions. We also see in this scene that at first Marianne is incapable of believing that Elinor could have felt the same amount of love for Edward that she feels for Willoughby, but when Elinor explains her sense of duty, and that, had she not been sworn to secrecy, she could have shown just as much grief as Marianne is showing, Marianne feels absolutely ashamed, saying, "You have made me hate myself for ever.--How barbarous have I been to you!," showing us that Austen is characterizing Marianne as being capable of understanding, sense, reason, and selfless love, even though her drive to violently express her emotions makes her selfish at first.