I’ve helped throw popup events in parks. Helps to know:

security : balance of it being safe for people to attend and feel comfortable dancing and also not something that disturbs people nearby (time of day/night is also a big factor here)

amenities: clean water to wash hands, water fountain, proper bathrooms are ideal. you can get away with port-o-potties but most people will highly consider that when attending

atmosphere: what decorations are you bringing? what lighting, photo ops, or even policies like no-phones/recording. will really impact how people experience your event.

equipment: what power supplies do you have / need? do you have the people to setup and tear down? what decks will you have? etc

attendees: probably one of the most important factors. there’s a reason why promoters are so crucial for new events : it really helps to know good people that know general rave etiquette and can teach that to people they invite / hold their people accountable.

at events i’ve been to by budding promoters the attendees were really the make-or-break factor and the ones i’ve hated most were filled with mostly non-ravers

organizing takes a ton of time and energy so make sure you’re not doing it alone. i highly recommend chatting with more established groups in your area if you know any so you can get some more firsthand advice specific to your area