Best way for a find a A

Hi.

ofter, it's very difficult to find a target audience.

example: if i Need to sell a drone?

how a can to find the best target? what is the best way for create an audience?

-i tried to create a campaign to interaction with a video drone.
-after i create a custom audience with all the people who interacted with my ads.
-After i created a conversion campaign with this audience but i have not conversion

Thanks