I don't know if they're "boycotts" or just "preferences", but:
- I try not to eat at any place that is a multi-state chain or franchise. No fast food, no TGI Fridays, no Domino's pizza, etc.
- I avoid shopping at as many "big box" retailers as possible: Target, Walmart, Best Buy, etc.
- I don't drink soda, but that's because I just don't like it. I do drink gallons of seltzer, though.