In my Intro To Logic class that I took a long time ago, the teacher led the class in a deduction about evolution. You could basically lead her through the deduction and invite her to poke at the premises, yourself, if you are confident enough talking about it. You could even sketch it out on a napkin in a restaurant. If my outline is insufficient, just let me know what I can do to help you flesh it out to your satisfaction.
1) Scarcity - there aren't enough resources for everybody to get all of what they need/want. (In my experience, some Christians deny this, claiming god will provide. You could easily counter that if that were the case, there'd be no such thing as economics. Or point out that there's half a million people starving to death in Botswana who might disagree).
2) Variability - There's differences between individuals in a population (I haven't had any trouble with getting people to agree to this one).
3) Inheritance - Differences between individuals can be passed down to descendants (They might need a prod by saying that kids grow up to look like their parents, or something like that).
4) Because variability can be passed down to future generations (via 2 and 3), any variability that makes you better at getting a bigger slice of scarce resources gives you a better chance to have babies.
I know it isn't technically a deduction, since I didn't introduce every term and show how P1 & P2 => C1, etc, but I imagine formal logic isn't something your friend cares much about.
A biologist friend of mine has had limited success with this method. He has also suggested that the book "Why Evolution Is True" be read by novices who are open to actual dialogue but don't know enough to accept evolution.
I suspect this would get J. Random Creationist to accept small-scale evolution but not large-scale. The better-informed class of creationist doesn't even attempt to refute things like Darwin's finches; they'll instead come up with reasons why those arguments don't scale to full-blown speciation.
One thing leads to another, and before you know it you're trying to demonstrate why tree fossils crossing strata don't actually prove Noah's flood. This is less of a problem if you're not dealing with a young-earther, of course.
I have a creationist friend with no particular rationalist or scientific training. She recently asked me to send her a "list of evidence for evolution that persuaded me." After some prodding, it was revealed that she's getting into an argument with another friend of hers who believes in evolution. I'm assuming that she wants the experience of arguing with someone who's on level footing with her. It seems like a good opportunity to broaden someone's mind in a more general way that'll benefit them in the long term. I don't particularly care whether she believes in evolution (it probably will not impact her or the world in general if she changes her mind about it). But I'd like to phrase my e-mail in a way that's most likely to cause her to re-evaluate her worldview.
Subgoals related to this:
1. Point out that "losing" an argument can allow you to learn things, and if you honestly care about truth you'll try your best to evaluate ideas from other points of view and consider what it would mean if they were true. Do this without sounding condescending.
2. Give her a line of retreat by proposing that evolution is compatible with the Original Sin interpretation of genesis (which is very important to her and I would never attempt to argue against).
3. Give as much background as possible on the scientific method.
4. Still manage to focus the bulk of the e-mail on the most persuasive facts supporting evolution, otherwise I'm obviously not satisfying the criteria she actually gave me. I don't mind taking advantage of her request for my own purposes, but only if I'm actually helping her with her stated goal.
5. Specifically show why macroevolution is not only possibly but likely. (I'm pretty sure she either already believes or could be easily persuaded to believe in microevolution)
6. DON'T focus too much on why creationist arguments are flawed (she hasn't even used any yet, and it sends the wrong message about trying to actually figure out what the truth is)
7. Accomplish everything in approximately 3000 words, without using jargon, designed to be read by someone who's mental architecture isn't particularly adapted to rationalist thinking. (Most people aren't.)
I believe I can do a decent job myself. But it'll be a fair amount of work, and I want to know if anyone had a recommendation for a particularly good essay that I can either link her to or borrow pieces from. I might also include a link to a page of common bad creationist arguments and why they don't make sense.