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Shake hands with a solid, firm grip, and look right into that person's eyes. If your culture has a different way to greet others, use that form in an appropriate and polite way. When you meet someone new, make a good effort to remember the person's name by repeating it: “Nice to meet you, Wendy.” Good manners communicate that you respect the other person, which is the behavior of a mature person.  Throughout any conversation, listen carefully and maintain eye contact. Don’t stare at the other person, though. Use the 50/70 rule: make eye contact for 50% of the time when you’re talking, and 70% of the time while the other person is talking.  Avoid fidgeting or fiddling with random objects. Fidgeting is a sign that you lack confidence. Keep your hands open and relaxed. Don't sit there thinking about places you'd rather be. Most people are very good at noticing when you don’t care about an interaction, and it will hurt their feelings. Don't talk on your cell phone or text people while you should be paying attention to the person in front of you. This communicates disrespect. When you enter a new situation or new community, keep quiet for awhile and notice how other people are acting. It's not your job to tell other people what they should or shouldn't do. Instead, watch and be respectful. Using good online etiquette shows that you respect your friends, family and other people that are hanging out with you online. It’s a sign of maturity. Keep in mind that a lot of what you say online can also be seen by people like potential employers, teachers, and others, so don’t say things that would embarrass or hurt you.   Avoid strong or offensive language. Don’t overuse exclamation points. Remember that you aren’t there in person to clarify your point, so make sure not to overwhelm your audience. Use your shift key. Capitalize proper nouns and the beginnings of sentences instead of writing in all lower-case letters. Avoid using nonstandard cApitaliZaTion. It makes your writing much harder to read. Avoid using ALL CAPITAL LETTERS. This is the internet equivalent of shouting. This may be okay if you’re posting a tweet about how your hockey team just won the championship, but it’s not a good idea in daily emails and social media posts.  When sending an email, use a salutation (the “Dear” in “Dear John”). Starting an email without one is rude, particularly if it’s to someone you don’t know well or to someone like a teacher. Also use a closing, such as “Thank you” or “Sincerely.” Proofread before you send an e-mail or make a social media post to make sure you didn't make a mistake. Use complete sentences, and be sure to add proper punctuation at the end of each sentence. Go easy on abbreviations, slang and emoticons. It's okay to use these in a casual text to a friend, but don't use them in an e-mail to your teacher, or in another situation where you want to look mature. Remember the golden rule online, just like the golden rule in real life. Treat others the way you want to be treated. If you want someone to be nice to you, be nice to them too.  If you don't have anything nice to say, don't say anything at all. Hold doors, help pick things up, and offer assistance to anyone who needs it. Consider being helpful in your community as well, like being a mentor to a younger student, tutoring, or working at an animal shelter. When you make others happy, you’re more likely to feel happy yourself. Serving others rather than just yourself is a very mature behavior.  Helpful acts may also boost your self-esteem. Studies have shown that when we help others, we get a sense of accomplishment and pride in what we’ve done.  Being helpful isn’t always a two-way street. There may be times when you help others and they don’t say “thank you” or offer to help in return. That’s on them. Remember that you’re being helpful for you, not to get anything from anyone else. When you constantly take over conversations and talk about yourself all of the time instead of giving other people a chance to talk, it shows disrespect and immaturity. Showing a genuine interest in the interests and experiences of others can make you seem more mature and less self-centered. You might also learn something new or develop a new respect for someone based on what you hear. If somebody compliments you, say "thank you" and leave it at that. If someone criticizes you, be polite and say something "Okay, I'll definitely think it over." Maybe the criticism isn't valid, but handling it politely makes you look mature in the moment.  Try not to take criticism personally. Sometimes, people may be trying to help and aren’t communicating well. If you think that’s the case, ask for clarification: “I heard you say that you didn’t like my essay. Could you tell me some more specifics so I can do better next time?” Sometimes, the criticism says much more about the person giving it than it does about you. If the criticism seems unfair or hurtful, remember that the other person may just be trying to make him or herself feel better by tearing you down. Don’t let it get to you. Accepting criticism gracefully doesn’t mean you can’t stand up for yourself. If someone hurts your feelings, tell them in a calm and polite way: “I’m sure you didn’t mean it this way, but when you criticized my outfit it really hurt my feelings. Next time, could you not make comments about my appearance?”

Summary:
Use good manners when you interact with people. Observe good online etiquette. Be helpful. Avoid trying to be the center of attention all the time. Accept both compliments and criticism with maturity.