Cinematographer here. It is a very expensive industry but everybody starts somewhere and the technology has improved so much that even no money productions are doable now.
Shoot on your phone. Shoot outdoors. Use your mates as actors. Writing a script costs nothing but bare in mind everything you write could cost you money to acquire. The clever bit is how to write that without it costing much.
Above all story and characters are the most important so focus on those rather than expensive gear.
There’s also some great books out there. The guerilla filmmakers blueprint helped me out a lot when I started out.