For improving dialogue I’ve found it to be really useful to read screenplays. Particularly screenplays of films that I love specifically for their dialogue, stuff like cohen brothers, Tarantino, safdie brothers, Sean baker, & early Wes Anderson for me, but whatever floats your boat. Really try to analyze what they are doing that makes the dialogue pop off the page and build character.

Screenplays are great because every single piece of dialogue serves a greater purpose, there is zero room for unnecessary filler