I come off of a weekend where proper planning deterred attendance and visibility of events.
Basically you have to get the word out using EVERY form of communication available. You can use formal advertisements as well but getting that word out is clutch.
Know your audience, who needs to be invited and ensure they not only know but they have ample time to plan for coming. If they desire, they will be there period.
So if you want to help advertise or promote an event, you must be relentless and ensure your audience knows all of the important details: the date, time, location and costs.
Everyone will not come but you have to build that visibility and notoriety to your event. We’ve been in the pandemic for two years and people are anxious and ready to get out.
Surround yourself with people that have the bias for action to get this done, and delegate responsibilities that they will be best at. It’s no fun having to do it all with very little help. You may be better off calling off the event.
Also if the cause is worthwhile, don’t give up the first couple of times. Learn from your mistakes, know your audience, promote and keep working at it!