Based on who your target audience is, you will want to create specific tags that make sense to you and your business.
Ideally, your tags tell you where the person you are talking to is in your sales cycle.
Here are a few ideas for tags that I personally think might be relevant:
New- This is simply the default tag that will be assigned to every new person you will be talking to inside your Facebook messenger.
Follow Up- Everyone you simply need to follow up from time to time to see what they are up to. They might be a good fit for what you have, but you aren't sure yet.
Potential Lead- These people might be a good fit for what you have, based on the conversations you had. It didn't get to a sales conversation yet, but you know that your product might solve a problem they are facing.
Hot Lead - These people are the closest to buying something from you. They know what you offer and they have expressed a strong interest in it. They might still be on the fence and are thinking about it. Make sure to follow up with them and close the sale.
These are a few of the essential tags. If you have a specific audience in mind where a specific tag makes sense, use it.