I've been working on a scene with two women, and have been editing with an eye to clearing up the confusion of the pronoun. So here are a couple suggestions:
Situation-- two women interacting, talking together in a scene. So "she" could refer to either of the two women. And you're going to have sentences that involve both of them. ("She handed her the two-liter bottle.") So think about what problems this would cause for your narration, and how you'd handle that.
1) First, I'd try to make the names not start with the same letter. Sophisticated readers probably often "read" the shape of the word on the page or screen, rather than seeing the letters. Usually, they'll see that initial capital and associate it with one character another, and then quickly go onto the next word. This subconscious process is impeded when two character names start with the same first letter. So reconsider "Jane and Jackie"... but do it early, before the name becomes bonded to the character. You know how that happens. "But she IS Jane!! I can't make her Eve! I can't!"
2) Who's in viewpoint in this scene, or at this point in the scene? We tend not to think of ourselves as our names, but rather "I," and the equivalent of that in third-person is the personal pronoun he/she. So one way is to make she/her/hers always refer to the woman whose viewpoint we're in. (This only works with tightly controlled POV that stays clearly in one character a long time, preferably the entire scene.) But then you have to refer to the other character by name, even when you're using the possessive case. So "She watched Jackie comb Jackie's hair..." Nahhh. :) Some variation of the POV-character "she," however, seems to be what most of us end up with.
3) Use their names when there's any confusion at all. Clunky, yeah, but clunky is better than unclear. So "Eve watched Jackie comb her hair" works because we're going to assume the "her" refers back to the last name (Jackie). How would you do it if Jackie's a hairdresser and is combing Eve's hair, and Eve can watch it in the mirror? "Eve watched Jackie comb Eve's hair" is TOO clunky.
4) Recast whenever you can't make it work. Try putting one person in a dependent clause and the other in the main clause, maybe: "As Eve watched the process in the mirror, Jackie combed out her hair." Arrrgh. This is always hard. Two sentences might be necessary. Well, so what? Not like you're limited to a certain number of sentences.
Supply some examples of tough sentences with two "she" characters, and let's see what we can do to make them comprehensible and unclunky.