If I want to change a collectors code, and work with it, what is the best way to setup a project

[ggoldber]

If I want to change a collectors code, and work with it, what is the best way to setup a project that will pick my own changes, instead of the one in the official repo?

[Rohlik]

You can do a fork https://github.com/open-telemetry/opentelemetry-collector/blob/main/CONTRIBUTING.md#fork, then do your changes.
You will need a few tools, list here - https://github.com/open-telemetry/opentelemetry-collector/blob/main/CONTRIBUTING.md#required-tools