I would suggest starting with individual study and observation. Too much activism is pushed from emotion, and it all reaches a point where it just comes across as noise. I think what's needed is a balance of the passion combined with knowledge and understanding.

Getting involved in local politics and making small changes in a progressive direction as opposed to trying to save the world. A good example are communities that are supporting local growers/producers and freeing them from some of the national/state level red tape. Improving the chain of supply more locally and increasing awareness. This is much harder in larger cities though... as local foods are less diverse and less universally available year-round.

Working with local restaurants that aren't chains and trying to build local sustainable menus. Moving away from refined products to more local.

As it stands, it's very niche and trendy, which can come across as off-putting or out of touch. But working locally can be very impactful. If you can convince one restaurant to move at least part of their menu to local supply, that can help. Being closer to the source will lead you to connecting with the source and having a better understanding.

There are a lot of people out there, working on actually making their small parts work... connecting these people is really hard. I've been pushing for years talking to local restaurants to try to get them to move away from refined seed oils for cooking alone, and it often falls on deaf ears.

Shop and advocate for local coop markets that have sustainable practices.

Unfortunately, it's hard to fight the convenience/abundance of Wal-Mart, Amazon and Costco. I have enough trouble convincing my SO to hit a couple different grocery stores in a day, as opposed to trying to get everything needed in one convenient stop.