Some of this stuff got passed around in e-mail with my buddies, they're the rules I've gradually built up when e-mailing chicks, either initially or in responses to them. Whenever in doubt of how to proceed via e-mail with a chick, refer to these rules. Keep in mind, though, that you ultimately want to focus on using the phone when communicating with a chick, limiting e-mail contact, and only use e-mail/phone if it progresses you to your ultimate goal (a lay ... if that's not what you're looking for, you're reading the wrong web site, LOL). Even after achieving your goal, don't lax on these rules. This advice isn't for guys who are already good at handling chicks through e-mail, applying their own methods, it's for guys who need a guiding hand...
Pre-rules (with some clarifications on contact closing in general):
1. Focus on g closing ("girl closing") before ever focusing on getting a chick's number or her e-mail address. The priority of close goals on first meeting should begin with an f close. Next is g close. Then a contact close. And, don't bother with contact closing unless you've properly g closed.
2. If you don't manage to get a same-day f close after first meeting a chick, and have to default to getting a chick's contact information for a future follow up, @close at the very least. If you want her number, start by @closing and then finish up by #closing. If she's reluctant to provide her number, then you haven't properly g closed. You're left with a choice of either reverting back to building up her interest or (better) challenge her in some way that displays your strong belief in your self value (for example, giving her back the piece of paper with the address on it and saying "Sorry, I'm not into playing games and am not going to e-mail you if that's the case. Otherwise, if you're really interested in having me get in touch with you later, then it's OK to go ahead and write your number down.") If you get her number first, still get her e-mail address, if she has one.
3. If a chick gives you a number or e-mail pretty easily, yet you're not sure yet of whether you've properly g closed, you can attempt this test which I sort of picked up from David DeAngelo: Look at her semi-suspiciously, but with a knowing smirk and, with a teasing tone, ask her (while handing her the piece of paper back, or before entering the # into your cell phone), "Is this a number you actually answer?" If she challenges why you're asking, finish handing her the paper back and tell her (in your own words) that you're not interested in wasintg your time calling a number that only has an answering machine attatched to it. Be VERY consistent with these words and be completely willing to walk away. If you pull this off right, only 3 situations will play out. She'll either insist the number is good and hand you the paper back or finish giving you the number, or she'll admit that it's her cell's voice mail which she never picks up (or whatever) and proceed to give you another number, or she'll bitch you out or some other shit because the reality is she was giving you a bogus number (but won't admit it). In the last case, you've saved yourself the hassle of getting in contact with her later.
4. This one I got from TokyoPUA. If a chick gives you her number, call it right in front of her after you enter it in your cell. Joke with her about it, that you want her to leave a message for herself (or whatever else is funny at the moment). If she's given you a bad number, you'll know right away, and can bust her in real-time. Otherwise, it's a great anchor for later as she'll get to hear her happy voice (and maybe also your voice) on her machine at the time she was talking to you. This is optional, but if you're a guy who constantly gets bad numbers then try it out a few times.