According to Taté Walker over at Everyday Feminism, you can:

1. Support Native American artists
2. Learn about (and consider backing) Native-led movements
3. Call out appropriation because it’s offensive (not because you know I won’t like it)
4. Support non-Native companies or organizations that actively honor Native culture and/or creations

http://everydayfeminism.com/2014/08/honor-native-americans-without-appropriating/