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Chances are, if you stumbled across someone's profile on Facebook, you have a friend or 2 in common with them. Click the "Add Friend" button on their profile to connect with them if you're interested. Sometimes, people won't accept friend requests from people they don't know, even if you have friends in common. If you don't hear from them, don't be offended. You can try asking your mutual friends about that person to see if you can all hang out together at some point. If you've met them in person, try to send them a friend request within 1-2 days so they remember who you are. If they update their photo or post a new status, use the like button to show that you saw it and are paying attention to their posts. This is a great way to get yourself on their radar and to get them to notice you on Facebook. Don't like more than 2-3 statuses or photos at once, since this can flood their phone with notifications and make you seem annoying. You can like a recent post as soon as you become friends with someone, which will let them know that you looked at their profile and enjoy their posts. The person you're interested in might be pretty active on Facebook, so take the time to comment on any status updates with kind, supportive sentiments. This will show them that you're paying attention to their posts and can open up a more private conversation in the future. For instance, if they post a picture of their food, you can say something like, "Wow! That looks so yummy!" If they post a life update, like a move or a new job, feel free to comment with a "Congratulations" or "Good luck!" This is a great way to show someone who you have a crush on in real life that you're thinking about them. You can tag them by typing their name and selecting it, or you can send the post to them in Messenger by clicking the "Share" button. Try not to tag people who you've never met in real life or who you don't know very well. This can come off as annoying or even creepy if you've never really had a conversation. Try not to seem too overtly flirty on their posts since Facebook is a public forum and they're likely friends with their family members and coworkers. Keep your comments positive and friendly, and remember to stay polite when you're ready to send them a message. As a general rule, try not to make comments about their appearance, as this can be embarrassing. Instead, focus on being kind and friendly so that you can eventually send them a message to continue the conversation.
Send them a friend request if you have mutual friends. Like someone's photo or status to show your support and interest. Comment on their status updates and pictures to interact with them. Tag them in a funny post if you're friends in real life. Be polite in all of your interactions.