Brianruns10 wrote:
Just googled her name, and the first thing to come up was her official website (she's a local actress), and it had her email. Simple, something anyone could do, so it's not like I did a huge, stalkerish search to find some obscure info on her.
1) What wolfheart said. Tone it down/keep it casual
2) You wrote something for a project that's actually in production? Congrats--own it!
My two cents below. Feel free to edit (or ignore. Just trying to share from experience

(this is coming from the perspective of someone that used to "script" a lot of social situations).
Things to consider in asking for a date: Context, Identity, Compliment, Interest, Request
Hi X,
Thought you were great on [Name of Project]. I wrote the script (and did the 'magic fingers')--would like to hear your perspective on some other projects I'm developing. Would have liked to talk to you more during the shoot, but were both pretty busy. Dinner at [local resto]? Next Thurs works for me--would that work for you?
Cheers,
[Name]
[Mobile]
Email is a brief, casual medium so you will want/need to be both. Start general (you were great!). Combine the compliment with identifying yourself (so she associates you with compliments!). Next, establish interest. "would like to hear your perspective" is pretty weak I know, but I think you get the gist; edit accordingly. You want to hear her opinion on the experience you have in common. People in general, women in particular, like to know their opinions are valued. For the request, be specific but flexible. Suggest a location and date. Date should be no less than 3 days in advance and no more than 7. Suggest a date too soon and you appear to presume that she (and you) have nothing else to do ("I'm standing outside your window. Wanna have coffee?"). Too far in advance and you appear pretentious ("verily, I date many a lass and shall therefore schedule you a fortnight hence")
Since YOU sent her an email, YOU are establishing email as the preferred form of communication. Include your mobile, but not as part of the message. If she wants to call you, she will. If she wants to you call her, she will send you her #. If she doesn't reply, wait a week, then send a send a cheeky follow-up: "Hey, free dinner with a scriptwriter--how bout it?

"
I don't think you need to worry about how you got her email. You're the scriptwriter so its reasonable that you'd have access to her portfolio, etc.
Good luck dude. If it doesn't work out, keep writing scripts for projects that get produced and I'm sure you'll meet a few more actresses.