We won't attempt to cover event planning in depth here. Plentiful coffee and strong wifi are not optional, but there is considerable flexibility on the rest.
Be sure to consider booking blocks of hotel rooms or dorm digs at a reduced conference rate. Make sure that you select clean, decent hotels in safe walking proximity to your event, and that participants are provided with maps and plenty of orientation materials before arrival.
Solicit enough information from participants to allow you to create a public list on your website, including images and brief bios, if desired. Be aware that not everyone will have a Gravatar!
Be clear in the material you distribute ahead of time which meals (if any) will be covered and which ones participants will be responsible for purchasing.
Be sure to make attendees aware of the location of restrooms — including unisex facilities, if possible — and private spaces for nursing mothers.
Remember that the break-out sessions are where people connect and where the most important conversations happen. Make sure there will be enough space for several groups of varying sizes.