how to join a conversation

Sense the openness of the conversation. Take the time to observe if the conversation is open or closed, by looking at the body language of the people involved. If it seems to be a serious conversation, or a closed conversation, they may not prefer to have anyone join them. If the group seems more open, take the opening as a sign that it’s okay to move forward with joining the conversation.

In an open conversation, you may notice open arms, speaking in louder voices, and a larger or more open circle.
In a closed conversation, you may notice closed or folded arms, speaking in low voices, and being physically closer to one another in a tighter circle.

Naturally position yourself. As you move a little closer to joining the conversation, try and have a reason to be close to the group that would allow you to naturally overhear them. Without a natural reason to be closer to the group, your presence may been perceived as eavesdropping, lurking, or creepy. Some natural ways to get closer to the group include:

Refilling a drink
Getting some food
Waiting in a line
Studying movies or books on a shelf or art or posters on the walls.

Listen. Before jumping in take some time to listen to what they are talking about. Listen for what kind of conversation it is and the topic of conversation before jumping in. This way you will be well prepared to know when it is appropriate to give your opinion or ask a question.

Is it a more serious or somber conversation? Is the topic of a personal nature?
Is it a more comical or topical conversation? Is the topic more of a causal nature?
How interested are you in the conversation?

Check in with yourself. The biggest conversation-killer is self-consciousness. Your anxiety and comfort level will have a great deal of impact on how easily you join a conversation. If you are nervous, intimidated, or shy, try taking a couple of deep breaths. Know how you are feeling so you can be ready to seize a fitting opportunity when it comes your way.