3 common Slack mistakes to avoid:

Avoid sending multiple messages in a row. This can be disruptive and overwhelming for other community members, especially if they are not available to respond right away. Instead, try to combine all of your thoughts or updates into one cohesive message.

One common mistake people make is to reply in-channel instead of in a thread. This can create clutter and confusion within the channel, making it difficult for community members to follow the conversation.
When you reply in a thread, it keeps the conversation organized and contained to the specific topic at hand and also helps to reduce notification overload for team members who may not be directly involved in the conversation.

1) Hover over the message that you'd like to reply to.
2) Click the 'chat/Reply in thread' icon.
3) Type your reply.
4) Send your message.

It is generally considered poor practice to post the same message on multiple channels on Slack. This is because it can be considered spammy and can be disruptive to other users who may see the same message multiple times. Additionally, it can cause confusion and make it more difficult for users to follow conversations. Instead, it's recommended to post the message in the appropriate channel and direct users to that channel if they are interested in the discussion.