If you spend enough time on Twitter, chances are you’ll come across an occasional chat being held on the platform. Twitter chats are scheduled gatherings of people on Twitter to discuss pretty much anything that interests them, using a #hashtag to keep track of the conversation. There are chats for everything from blogging to art to agriculture — over 80 of them are listed in this great running list of Twitter chats.

Here are some tips and tricks for how you can start and run your own chat on Twitter.

1. Choose a Time, Topic, and Tag

The first thing you have to do is choose a topic. Unless you’re looking to start a competing chat, you’ll probably want to choose a topic that isn’t already being done, so ask around, do some searches, and check the Google Spreadsheet linked above.

You’ll also want to make sure you pick a time that doesn’t conflict with a pre-existing chat in topic areas that might attract similar chatters. Ask around and make sure there aren’t many other chats at the same time, especially if it’s something that both audiences will be interested in. Choosing a time can be the toughest part. Just realize, you’ll never be able to please everyone. I suggest choosing a time that works best for you, to make sure you’ll be committed to it.

Your chat’s hashtag should be as short and explanatory as possible. Everyone who participates in the chat will have to use the hashtag with every tweet, so the shorter the tag, the more space they have to write chat messages.

2. Choose a Format

There are a number of different formats that chats can take:

1. Single Topic, Question Based

This is how I run the chat I am involved with. We choose a general topic, then ask specific, numbered questions throughout the chat within that topic. Each question gets roughly 15 minutes, and the chat lasts one hour.

2. Multiple Topic, Question Based

The longest running chat, #journchat which was started by Sarah Evans, uses this format. All questions are submitted by participants and numbered. Any topic goes, as long as it’s related to PR, Journalism, and Social Media.

3. Single Topic, Freeflow

This is how Mack Collier runs #blogchat. He chooses a topic, and just lets the discussion take a life of its own. This chat runs for 2 hours.

4. Q&A

Jay Baer runs a different kind of chat. He brings in a guest to answer 20 questions over 90 minutes. While the focus is on the guest, many people follow along and share their thoughts on the questions as well.

5. Free For All

No specific question, just bring everyone together and let them ask whatever they want. It’s a bit messy and I haven’t seen any chats adopt this format permanently, but I’ve seen a few try it for one week and the results have been great.

3. Launch the Chat

Of course, this will be easier for some than for others, depending on how engaged you are with the audience that you’d like to participate.

Promote it to your community leading up to the chat. Let people know beforehand when they can join and how the chat will be run. It may be smart to reach out to a few key people personally and ask them if they’d be interested in participating.

Be prepared for a slow start. Like any community, a Twitter chat takes time to build participation.

4. Tips to Help Your Chat Grow

Whether you’re starting a chat for business or for fun, I can tell you that it is an extremely rewarding and exciting experience. It’s an opportunity to bring people together and engage in valuable and insightful discussion.

If you’re starting it for a business, it is best to choose a general topic that relates to your business, and always keep in mind that these chats are for the community, not for the hosts. If you’re too promotional, your chat will fail.

Here are a few tips to help make sure your chat is a success:

* Stay open to new formats. #journchat got so popular that Sarah Evans began to look for new formats to host the chat, including video streaming, and even a country-wide live event. Always stay open to changing things up based on the community’s needs.

* Bring in guests. Every chat I’ve seen has at some point, brought in a guest moderator to host the chat, or a guest expert to take questions. It’s a great way to bring in a lot of new people and bring credibility to your chat.

* Take the chat beyond Twitter. A monthly chat for public relations students called #PRStudChat created a LinkedIn group for their chat, for example. They use it as a forum for the community to interact, and for them to share announcements and ideas.

* Consider multimedia. The weekly #DesignChat streams its chats live on video each week. The chat’s host and guests interact with participants over Twitter and answer questions on video. Video services like Tinychat (and Ustream) integrate with Twitter, making them ideal platforms for Twitter chats.

* Promote your participants. At #u30pro, we send out a weekly digest every morning after the chat, in which we announce a “featured participant,” share 5 blog posts from the u30pro community from that week, write a recap of the chat, and more. Highlighting community members and the things they’re doing gets people more engaged.

* Keep it up! Luckily, Twitter chats are inherently viral. Because when someone participates in your chat, all their tweets appear in their stream with your hashtag, and they bring in their followers. As long as you keep to your schedule and keep holding regular chats, the chat will pick up new participants over time.