To build on Guri’s insights, and to also help with finances, plan extensively around your venders/booths and building interest.
Aside from workshops and guest speakers/sessions, the vendors and booths make up a large chunk of “things to do” at a convention. The best part is that they are a win/win/win if done right – meaning the attendees are happy to have exciting products/vendors to visit with and/or purchase from, vendors get to talk about their product/service and make sales or potential sales (or at the very least get their name out in front of a desirable market), and finally you’re happy because your attendees are happy and the vendors are helping to pay your bills.
Before jumping headfirst into finding vendors/booths you need to have a solid idea of what exactly your convention is going to be and the market of people you will be appealing to. Once you have a strong idea of this, you need to put it onto paper. Make up a rough markup copy of everything: general overview (primary theme, secondary theme, etc), some specifics (i.e. time, possible locations, size, etc.), audience type (i.e. age range, gender, interests, median income if applicable, etc.), and finally why this specific vendor would want to come (write them out a summary, look into their business and know what they sell/service and why your audience is good for them).
Next you will want to also look into a sponsorship program to also help pay bills. You can brand anything really, they key is getting vendors to want to help brand it so you can give it away free while also offsetting the costs of your speaker’s air travel. To start I would personally build a “partnership/sponsorship packet” which would outline in more detail all the audience and convention details. Additionally, you make levels of sponsorships with a single “gold member” level available. I usually build out 3-5 levels of sponsorship which each has more benefits and cost than the previous. For example: level 1 = logo on t-shirt, company overview and logo in directory/show guide, and logo on website with additional mentions throughout convention over loudspeaker with booth location, 2 = all benefits of level 1 including company logo on hand bag handouts at the door and on banners behind main stage…… gold level = only one available, includes all benefits of other levels, opening comments before main speaker, co-branding on social media sites for convention, and exclusive lunch for VIP guests with company branding.
Once you have the sponsor handout information built, start sending out to applicable vendors – which can also include companies/groups outside your direct market that might also touch your audience base (i.e. local art studios, shops, etc). You can do something similar for your food vendors too, which is always nice to be able to have food on site to help keep people there.
Along with building the vendors list and sponsorship opportunity, you need to also build up the hype to get people to come so you can follow through with your end for your vendors by getting people to actually show up. Start by building your website so people can have something to find on the Google. Once that is up and running with your convention information outlined on it, start working with social media and forums to direct people to your website to sign up for additional information emailings, pre-register, or go to the FAQ section. This not only gets people to find out about it and get excited, but it also gives you a ground to stand on when reaching out to vendors (you look significantly more legit and invested when information is readily available and people are interested – making them more likely to pay you)
Once websites and social media are up, use them. Nobody likes stale information; update your audience on how things are going. Even if it’s talking about other conventions, tips and tricks, or why your convention is going to be the best, post it because pretty much anything relevant/appropriate is better than nothing at all. If you are lucky and have/get sponsors early on (especially your top sponsor) you can have a side agreement/discussion on giveaways leading up to the show – i.e. split the costs on an iPad, collector’s edition item, etc and raffle it off to those who pre-register by a certain date, but remember to advertise that everywhere you have access to if you decide to do that because just handing an iPad away to the one person who pre-registered is never fun.
Also in terms of volunteers – everything Guri said is spot on, especially thanking them. My experience with volunteers is to give them incentive and treat them like convention royalty. If you’re having a multiple day convention, I would offer up a free ticket for either the rest of the day or the next day access for sure, a free t-shirt (this not only gives them a t-shirt but also gives them something that distinguishes themself as volunteers and people can ask them for help if needed), supply them with a free lunch (could be as simple as pizza/sandwiches or as fancy as catered), and finally offer them a 10%+ discount on convention swag or onsite food. These all cost fairly minimum amounts of money in comparison to paying people to work, but really speaks a lot to the volunteers overall experience and happiness.