One of the team members of a startup that I advise told me that they were working to promote an event and were not able to do it well, because of several constraints.

One, they did not have too much time to promote the event.

They did not have an email list.

And, they did not enticing videos of past events.

If you are hosting an event and are in a similar situation here is what you should do.

Partner with people who have the audience you want to sell the event tickets to.

Offer them a revenue share option. 

Then ask them to send an email, host a webinar or a Facebook live for your event.

You help them with content for emails and webinar etc

This strategy will yield good results for you if you partner with a lot of influencers instead of just relying on one.

If you end up using it, let me know how it goes.