Introducing old friends to new ones isn’t always as seamless and easy as we’d like it to be. Your relationships with different people doesn’t guarantee that they’ll hit it off.

Now add decades that might include friendships from childhood, college, young adulthood, shared playdates, a series of workplaces, and more.

As we get older and our network of friends includes people we met at different stages of our lives, the chances increase that some might not mix well with others.

To help you navigate these often difficult waters, Considerable spoke with experts to find out the seven deadliest social sins to avoid, and what to do instead.

1. Don’t speak negatively about old friends to new, or vice versa

This might seem like a no-brainer, but you’d be surprised at how easy it is to slip into discussing someone’s flaws when describing them to someone else. Just remember that it’s not productive or helpful to tell a new friend something like, “Oh Carol is lovely, but she can be a bit dull at times.”

“The moment you do you are setting the stage for that person to be ‘branded’ as whatever you say about them,” Dr. Benjamin Ritter, founder and coach at LFY Consulting told Considerable.

Do this instead: Let your new friend make their own opinion about your older friend, and vice versa. By setting everyone up with only positive images of one another, you also help set up a much friendlier and more welcoming environment for all parties.

2. Don’t assume your friends will click because they both know you

Remember that humans are very complex creatures, and the qualities about yourself that bonded you to one friend might not be the same that bonded you to another.

Do this instead: Before introducing multiple friends, think of the things that they might already have in common or topics that they might both be interested in.

“Prompt certain topics you know that align with both friends. It’s your role to now be a ‘friend host’ where you will facilitate conversation that you know will bring people closer together,” Dr. Ritter said. “Do not bring everyone into a room and expect them to come out friends. You need to help create connections.”

3. Don’t blindside a new friend

Is there something your new friend needs to know about your old one(s) — especially if they may be outnumbered in a group dynamic? Are there certain political or religious topics that shouldn’t be broached? Ideas that might strike the wrong chord for someone? Make sure your new friend isn’t set up for embarrassment or awkwardness.

“Prep the ‘outsider’ friend before attending a group hangout. Let them in on the group’s sense of humor, politics, or habits.”
Danielle Bayard Jackson

Try this: According to Danielle Bayard Jackson, founder of the Give It a Rest Movement and author of the upcoming book Give It a Rest about navigating tough conversations with your female friends, “If possible, prep the ‘outsider’ friend before attending a group hangout. Let them in on the group’s sense of humor, politics, or habits. While you want your friend to have the freedom to learn the others for herself, providing context sometimes helps ease any impending awkwardness.”

4. Don’t bring up inside jokes

The longer the friendship, the more memories you’ve made together, and the more likely those are to slip into conversation. Remember, though, that talking about things that a new friend knows nothing about probably won’t make them feel very good.

Do this instead: “Try your best to stick to common ground. While it’s natural for inside jokes and strolls down memory lane to pop up in conversation, find a few things everyone is familiar with and work to incorporate them in the conversation,” Bayard Jackson said.

“You can also play matchmaker with your friends, helping them start their own conversation by making connections. For example, ‘Hey Donna, how is your new grandbaby? You know Christina just had a new grandbaby, too,’ ” she continued. “Making the introductions between friends from different spheres allow them the opportunity to create their own connections without you as a buffer, which helps the whole group to feel more familiar.”

5. Don’t disappear after introducing people

You’ve done most of the work facilitating and making sure your old and new friends had a good time together — excellent! But don’t assume they will carry on the friendship without you. If you want everyone to continue to meet up and get along, offer little pieces of encouragement from the other parties.

Try this: “After your get together, individually let friends know that another person in the group thought of them,” Bayard Jackson suggested. “For example, ‘Jan, we had a good time last night. Elizabeth thought you were especially funny. We have to get together again soon.’ This helps a mix of siloed friends look forward to the next gathering. When it comes to mixed friend groups, it is important to make everyone individually feels included, comfortable, and accepted.”

6. Avoid recalling awkward moments

“We’ve all had our share of embarrassing moments in our youth. And it can be hilarious to share that with close friends, but when you’re merging two friends or friend groups, everyone’s already a bit on edge,” Viktor Sander, B. Sc. told Considerable. “Sharing their past mistakes can make them feel uncomfortable and uneasy. Not everyone feels comfortable with their past all out there. It can make you feel trapped and vulnerable in a new and scary situation.”

“Present your friends in a warm, positive light, but keep it brief.”
Viktor Sander

Do this: “Instead, present your friends in a warm, positive light, but keep it brief. Tell everyone about your friend’s achievements or how they supported you in your past. Make sure they know how much you appreciate them and what amazing folk you think they are. That will make them feel welcome and accepted in this new situation.”

7. Avoid talking the most to the friend you feel most comfortable with

“If you know one friend better than another, it’s natural to talk more to that friend,” Sander said. “Don’t! That makes others feel excluded and like you’re not interested in them.”

Try this instead: “Make a conscious effort to keep both friends or both friend groups equally engaged in the conversation,” Sander suggested. “If you notice that one friend has been left out of the conversation for a period of time, ask them a question related to the topic you’re on. ‘What about you, John? What’s your favorite vacation spot?’ ”

A final note: It’s important not to stress out too much when introducing friends to one another. You want to let the conversation flow as naturally as possible and enjoy yourself as well.

Keep in mind that as the connecting link in the social circle, people will look to you if moments ever become silent or strained. Come prepared with these tips, however, and you’ll be in good shape!