I don't have an outline, but I have some insight:
Plath uses foils, doubling, and dualities to show the nature vs. nurture conflict Esther has within herself (her mental disease), with her mother, and with the society at large. Her main conflict in the novel is not with her own nature, but with the role and expectations of women in the 1950s who were supposed to put family above art and career. Plath focuses mainly on nurture, saying that the society is making her more sick than any inherited mental illness. In fact, many of the girls in the hotel are sick from the sexism that pervades the culture.
Sylvia Plath's foils in The Bell Jar serve to stifle Esther's decision-making by presenting two competing lifestyles which she cannot reconcile, thus compounding her flaws and making her more sick. As in her poetry, Plath uses mirror motifs in her characterization, paralleling Esther and Esther's alter ego, Elly Higginbottom, and pitting her feminist heroines against their paternal reflections. To Esther, these two gender roles are mutually exclusive, for males in the pre-sexual revolution have the freedom to choose from both sides of the fig tree, but women must choose one or the other. Esther wants to choose feminism, but she's been raised to choose the paternal path, so she chooses neither, retreating instead toward isolation and bitterness toward materialism, conformity, and the sexist social structure.
The fig tree pits the fruits of patriarchs against feminists, and Plath has each branch reflect "mirror image" growth. For every wholesome matriarch there is a feminist career-woman reflection. So, Sylvia stares at Victoria; Esther stares at Elly; Betsy stares at Doreen; her mother stares at Jay Cee and Philomena Guinea; and Dr. Gordon stares at Dr. Nolan. Her feminist Jay Cee (an obvious Christ figure) tells her to pursue languages, while her paternalistic mother advises her to learn shorthand. She wisely chooses the former and dates the interpreter Constantin, whose first date leads her to the cosmopolitan symbol of Plath's future Europe, the U.N. As foils to herself and Constantin, Plath uses the misogynistic trio of Buddy, Marco, and Eric to show the sexist hypocrisy and double standards of the 1950s. Whereas Constantin's motives are Platonic (he wants to explore Esther's mind), the trio's are chauvinistic (they see her as a sexual means to an end). They view women as either whores or virgins and cannot reconcile Esther's overreaching ambitions. Thus, Plath's male characters are reflections of either the husband who mistreated Sylvia or the father who died and left her at the clutches of an overprotective mother.