Sponsorship
Sponsorship can be a double-edged sword for a convention. On one hand they can bring in valuable funds and from publishers, AV and games companies valuable contributions in kind, from publishers and games companies, and tapping into the company's followers can broaden the reach of an event.
But often the companies most keen on sponsorship are ones wanting to improve their poor reputation, and attendees want to distance themselves from them. An awards ceremony with the winners photographed under a sponsor's banner can lead people to feel they are endorsing the company's morality.
Companies closest to SF are best, but even publishers are problematic, if their output is politically different to a vocal element of your membership.
When negotiating sponsorship, have a clear agreement on where the sponsor's logo will appear on your publications or on stage, is the deal exclusive such that rival companies logos' cannot naturally appear on equipment. Will rival companies be precluded from taking out ads. Are you obliged to refer to your event as the "MegaCo convention", as pomposity will be ridiculed by fans. Do you need to meet certain membership numbers to get the money?
How will you handle a boycott campaign started on Twitter?
Do not be tempted to pass on your membership list to the company so they can do a mailshot.