I take a pretty different tact. Here's my list:
What are you up to?
I go with this or a similarly general question path to mine what the person is needing a reference for. If I don't like the person well enough to care what they are up to, then that's a good indicator that I probably shouldn't provide a reference. But then I value a pretty diverse connection set.
Usually this is more along the lines of what is the person doing recently, what are they going for next (a job, a position in a volunteer group, academics, etc). That gives me a sense of what they want out of me as a reference without forcing them to commit to a certain set of positions.
I do expect that if they want me as a reference for, say, a job in the tech industry, then I'm not signing up to be a reference for something wildly outside that sphere.
What do you need from me?
Meaning more form-factor than specific characteristics. If you want a letter, then when do you need it? If you want a phone reference, then I better tell you that I'm easier to find by email, and they need to schedule time with me, because I'm that hard to get on the phone. There's a lot of logistics here that we better be clear on.
Also, this is a way to confirm why they are contacting me - personal or professional references are usually the big difference. But I have also written reference letters for visas, which can be a bit different in both format and intent.
Please give me a heads up
If the person is applying around for a bunch of jobs and they know when I'm likely to get called (usually in the tech industry, this is after the hiring process has gotten very likely and serious, if not after the formal offer) - then I ask that where possible they give me a heads up. With the understanding that sometimes this simply isn't possible.
I usually just ask for a quick ping to my email - the big deal for me is that my schedule and communication streams are nuts, and the more notice, the better. I want to make sure that if I commit to giving a reference, I will manage to be helpful and timely.
Send me your Resume
Let me have something to speak to, and that will let me structure my thoughts. I've been in the position of having worked with companies with multiple names - so it's especially helpful to have the resume and be able to say "Ah - yes - we worked together in XYZ Company". When fact-checkers call, they are likely to mispronounce, and reference companies strangely - so the better I can do at sounding clued in, the stronger my reference will be.
I may confirm general intent for content across these topics, but I won't make any commitment to what I'll say, nor will I ask for suggestions. Many times, it's irrelevant - having talked to my own reference-givers, I've found that all our Serious Talking about my current goals was pointless, because all the investigation did was verify times and places. Also, asking "any requests" implies that I'll do what you ask. I won't. People are mix of bad and good - if you trust me to be your reference, you'll have to trust that I'm not going to be a jerk. I will be honest, truthful and positive and do my best to put you in the best light, but accurately.
If I can't be honest and positive at the same time, I will not agree to be your reference.