Some guidelines on being a white ally:

Listen to marginalized communities issues more than telling them their issues.
Explain these issues to other white people outside marginalized communities.
Boost and lift up voices from people within marginalized communities.

If someone accuses you of bigotry, don't immediately defend yourself. Instead, pause and reflect.
Focus primarily on addressing systemic oppression, not individual people's bigotry.
Never reduce problems down to class struggle, or value class conflict above all else.

There will be people within marginalized communities who do not acknowledge their own systemic oppression, and/or are privileged in other ways. Address their privilege, not their oppression.
Lastly, no white savior complexes. Your job is to act as support, nothing more.