Talk with the group. Remember, nobody likes to feel left out. It's always appropriate to respond to specific comments directed to you with a reply that would be of interest to other chatters. However, personal conversations can be distracting. If you need to discuss something with another chatter, some chat software programs allow you to send a message to that person only.
Nobody likes a party-pooper.
A chat room should have a fun, friendly atmosphere. Sure, you can welcome newcomers to the room, but please be careful not to interrupt the conversation. When greeting, wait for the appropriate moment or defer to the judgment of the chat host, if applicable. Abusive or foul language, rudeness and personal insults aren't welcome in any chat room. Feel free to express your opinions, but refrain from demeaning another person.