To nurture a community, it is important to be consistent. Designate a regular schedule i.e. weekly, biweekly, monthly and stick to it. Frequent cancellations will scare off attendees. Plan activities and speakers for the next several sessions in advance. 
Break content into short, self-contained modules. It is easier to retain small chunks. Each module is a fresh opportunity for students to learn something new, even if they did not completely understand the previous module. 
Limit your session to one and half hours. The shorter your session, the more likely people will be able to fit it into their schedule.
Consider spreading your class over multiple sessions.
If your location requires that you reserve the room for longer than a single session, consider holding multiple sessions with different sets of people in tandem.
Publish the list of requirements, possibly with unit tests, so that each student can install the required packages before the day of the workshop. Reserve time before the workshop in case students have trouble installing packages.
Decide on a time and place convenient to the people who have registered. Make sure you have enough people who have committed to attending before you make reservations.  When reserving a room, estimate your audience count conservatively.
Publish the detailed content online to improve the credibility of your tutorial. Answer questions on technical mailing lists with a signature describing your upcoming workshop at the bottom.
Collect payment before your workshop and commit people to attend. Early bird specials encourage people to pay early. 
Ask each student how he or she expects to apply the skills learned, preferably before the day of the workshop. Then you can tailor content to specific applications, emphasize relevant points and strategize on how to best solve his or her problem during the workshop. Students are more likely to leave feeling they have learned what they needed.
For larger workshops, it helps to pair students so that they can teach each other while you are helping someone else. Knowledge and skill transfer is like heat transfer and flows down a gradient between people until they have no more to learn from each other. Rotate pairs to reset the gradient of knowledge transfer. 
Review the agenda of topics at the beginning and have a visual roadmap readily available so people can see where each topic fits in a broader context.
This is a workshop, not a lecture! Walk around, evaluate each student’s situation and give personal feedback.  Personal feedback is the reason people are coming to your workshop instead of watching a video or reading a textbook.
Give opportunities for students to perform. For the most part, students will love it!
People are more likely to be honest with their feedback in a one-on-one setting.
It is the only way you will learn how to improve.
|||(1, 2, 3, 4) Thanks to Cathaleen Kaiyoorawongs.|
|||(1, 2) Thanks to Brandon Levi and his Muay Thai class, formerly at FightHouse and now at Evolution Muay Thai.|
|||Start Your Own Seminar Production Business. Entrepreneur Magazine, 2008.|
|||(1, 2) Thanks to the Community Organizers BOF at PyCon.|