Collective:
-Regulate Polluting Industries
-Improve insulation in older buildings
-Build more apartments
-Put carbon labels on products
-Mandate higher build quality of manufactured goods
-Require that water pipes have pressure management and active leak detection
-Prioritize public transit over electric cars
-Halt all new road developments and just maintain them until public transit is good enough
-Subsidize Electric cars (second to public transit in funding)
-Establish support networks for people who are using older gadgets/cars/clothing to encourage solutions to make goods last longer
-Build more green spaces
-Create a program to recycle old clothing
-More widespread use of contactless payments
-Ban all fossil fuel ads
-Ban oversized vehicles
-Encourage the use of hatchbacks and sedans
-Towns sign plant based treaty
-Convert animal agriculture land to wild lands
-Ban private jets/yachts
-Design cities as more walkable
-Switch to renewable and nuclear technologies
-Support repairability
-Shut down all oil operations
-Mandate microfibre filters for washing machines
-Force companies to mine minerals from e-waste instead
-Give up half of the planet to nature
-Do everything to prevent and end wars
-Tax the rich and use the money for climate initiatives
-Switch to bidets to save trees
-Switch to super slippery toilets to save water
-Mandate all stoves to be electric
-Reduce concrete in constructions projects and opt for bamboo/wood construction
-Require all office work to be done from home for as much as possible
-Ban discrimination and promote affirmative action so that there isn't lost potential or innovation from disadvantaged groups
-Increase grid interconnections
-Implement waste-to-energy conversions for waste management systems (stopgap solution)
-Build robust high sped rail network and ban flights under 4 hours.
-Require much longer warranties on consumer goods
-Require all software to become open source after the company stops developing the code
-Patents expire after 4 years
-Ban cryptominning
-Increase energy efficient standards with new houses with solar panels mandatory
-Support political parties with green policies
-Boycott fossil fuel banks and switch to green credit unions
Individual:
-Switch to E-sim
-Switch to green burials
-Buy used
-Install geothermal heat pump systems
-Install smart thermostats
-Use shampoo/conditioner bars
-Shop at refillable container stores
-Buy stuff at the local store
-Eat plant based
-Switch to Ecosia
-Recycle
-Give homemade gifts
-Compost
-Be organized
-Avoid synthetic cloths
-Buy reputable carbon credits
-Install Linux on new/old computers
-Pickup litter
-Ride your bicycle instead of the car
-Adopt kids and companions instead
-Start your own garden
-Use older cars for more than 12 years
-Keep phone for longer than 5.5 years (easy to do with fairphone,iphone, pixel, samsung or android phone with unlockable bootloader)
-Buy Fairphones as they're the most repairable and have to 8-10 years of software support
-Buy Framework laptops as they're user repairable upgrade-able
-Use reusable diapers for your infant/toddler
-Buy goods within your continent to avoid cargo ship bunker fuel
-Use refillable water bottles for everywhere you go
-Demand that your investment/retirement program switches to green projects
-Switch to e-documents
-Track your government's climate policy by visiting https://climateactiontracker.org/countries/
I will add more to list as more ideas are thought of.
Anything that a carbon credit program reduces could be done without the carbon credit, but there are many carbon credit programs that accomplish nothing except acting as a smokescreen.