The key to this is remembering that any event branding or marketing material has to communicate in a way that excites and inspires participation, and furthermore any messages are delivered clearly, consistently and with impact. This is where the use of graphic design comes into play.
Event assets such as logos, information brochures, signage, name badges, banners as well as an online presence can help you achieve these goals, but only if they are done correctly.
By using the skills of a creative director, graphic or web designer, all of the above can be met in both a social and commercial context. After all, the aim is to make your key messages work together to build a coherent identity; which in turn encourages engagement, as well as value for your money.
Tell them and they will forget. Show them and they will understand. Involve them and they will remember.