I'm not an authority by any means, but checking the Truth and Reconciliation Commission's "94 Calls to Action" might be a good place to start.

I'm a teacher, so I have a lot I can personally do in this regard, but other professions might be different.

This all coming from an non-Indigenous person.

There are websites dedicated to indigenous businesses;

https://sac-isc.gc.ca/rea-ibd
https://chiefs-of-ontario.org/priorities/economic/ofnbd-listing/
https://indigenousthrive.com/
https://saskchamber.com/initiatives/indigenous-business-directory/
https://www.ccib.ca/main/member/

If you live by indigenous territory, attend events or buy items from stores there. For example: https://alderville.ca/alderville-first-nation/tourism-and-events/

If you are looking for a tattoo and live by Kingston, I wholly recommend https://www.instagram.com/johnnycats_tattoos/. Did fantastic work on my tattoo and looking forward to getting many more from Johnnycats.

You can write a letter to your MP asking to at least update the fucking language in the Indian Act.

Donate money to a community organization or if a community organization is fine with it, volunteer.

Tell racists and those that deny Residential school abuse to shut the fuck up. Edit: If you are going to argue with these kinds of people, remember that they will argue in bad faith. You are not arguing with them to change their mind, you are arguing with them to show other people that you are right.

If an Indigenous organization is involved in a high profile litigation, donate money for the litigation. The Courts are slowly trying to address the systemic issues in the law. Edit: From the article, https://www.gofundme.com/f/saddle-lake-cree-nation-treaty-health-legal-defense-fund?attribution_id=sl%3A3476c505-854b-40e0-9d0e-9fc69c234982&ts=1789022961&video_sharing=enabled

Edit 2: If you want to find Indigenous artists, there is the CBC Music show Reclaimed. On a side note, if you like variety in a music show, you are going to get variety with Reclaimed. You might get folk music then hip hop then punk then pop music all in the span of an hour.

Finally, follow the guidelines to be an ally:

https://guidetoallyship.com/
https://www.diversityresources.com/how-to-be-an-ally/
https://www.queensu.ca/indigenous/decolonizing-and-indigenizing/being-ally

To add to self educating comment, buying indigenous ABS supporting indigenous businesses too.