The most natural way to ask for someone's contact is to say why you want it, without hedging or asking permission. How you handle a no matters just as much.
Ask for their contact directly, and say why
You've been talking at an event for fifteen minutes and it's going great, but you need to leave.
"I've got to run. Give me your Instagram. I'm taking you for coffee this week."
Saying why you want their contact shows it isn't a polite follow. A statement, with your phone held out, carries far more weight than "could I maybe add you?": you've already decided you want to see them again, and they only have to decide whether they do. Say "this week," not "sometime": "sometime" sounds like politeness, "this week" is a plan. No need for "totally fine if not": if they don't want to, they'll say so, and a smiling "no problem, great meeting you" is the best way to close it.
If they hesitate or say "I barely use Instagram," say "no problem, great meeting you." Don't try another app.
When they ask "why do you want my number?"
You asked for their contact and they're a little surprised.
- "Why do you want my number?"
"Because I want to take you out. Today wasn't enough."
When they ask why, they're checking your intentions. Saying it in one line reassures more than talking around it or joking, and "today wasn't enough" also tells them why you want to see them again. Once they know what you want, they can decide whether to give it.
If they say no thanks after that, thank them and go.
When they hesitate, give them yours
They seem a bit unsure and don't want to swap on the spot.
"Here's my Instagram. When you're in the mood for that coffee, message me."
Giving them your contact puts the next step in their hands, so they don't have to decide on the spot. That isn't backing down: you've made clear you'd like to see them again, whether they reach out is up to them, and you won't hang around waiting for an answer. Skip "no pressure either way"; going back to your own evening says it more clearly.
Once you've given it, don't keep asking "did you add me?", and don't go checking their profile every day.
When they say no to swapping contacts
You asked, and they said they'd rather not.
- "Sorry, I don't really add people I don't know."
"Sure. Nice meeting you. Have a good day."
The moment someone says no, what they need most is to know you won't push. Wrap up quickly and warmly, without a string of "totally understand" or explaining that you're not a creep. Getting a no isn't embarrassing; how you react to it is what people remember.
Don't ask "why?" and don't say "I'm not a creep" or "what's the harm?"
If you'd rather talk on the phone first
You've swapped contacts, and you prefer a quick call before meeting.
"Texting gets misread. I'd rather talk first. I'll call you at nine tonight."
State your preference and the reason, then a specific time. A full stop, not a question mark: "call you at nine?" asks whether you may, while "I'll call you at nine." sets a time. If nine doesn't work, they'll say so and you pick another. No need for "tell me if you'd rather text": if they really prefer typing, they'll say it.
If they prefer texting, text. Don't bring up calling every time.
Reconnecting with an old classmate
You come across a middle-school classmate on social media you haven't talked to in years.
Long time no see
Saw your post and remembered us skipping morning assembly together
Moved on to skipping work now?
The best opener between old acquaintances is a specific shared memory: they'll remember you right away and feel the warmth. Saying why you're getting in touch now means they won't wonder whether you're selling something or after a loan, and ending on a joke is easier to answer than "want to catch up?"
Don't open by asking about their love life or inviting them to dinner. Reconnect first.
Swap contacts around a shared plan
You, them and their friends get talking about a market next month that everyone wants to check out.
"I'm going to that market too. I'll start a group chat and we'll all go together."
With a real shared plan, swapping contacts feels natural, and nobody has to decide on the spot how they feel about you. Starting the group chat makes you the one who gets it done, and afterwards you have a reason to talk and a concrete chance to meet.
If you really only want to meet one of them, make sure you genuinely organize the group outing. Don't use it as a cover story.
When they say "maybe next time"
You asked for their contact and they said "maybe next time."
- "Maybe next time."
"Sure, next time. Great talking today."
"Maybe next time" is usually a gentle no, and sometimes a genuine not-sure. Just accept it and don't treat it as a promise. If you naturally run into each other again, you can ask lightly then.
Don't ask "when's next time?" and don't hang around places they go to manufacture a "coincidence."
Asking a mutual friend for an introduction
You like a friend of a friend and want to get to know them through your friend.
"Your friend from the hike: I'm interested. Pass them my number."
Having your friend pass along your contact lets them decide whether to add you without turning anyone down face to face. Keep it simple and honest so your friend isn't stuck in the middle guessing what you mean; if they don't add you, that's the end of it, with no need for disclaimers in advance.
Don't ask your friend to talk you up or package you; let them decide for themselves. If they don't add you, don't ask your friend to try again.