I'll probably get crucified for saying this, but much as I like to see people talking about how they're chaning their lifestyles to make things better, I think the best thing anyone can do is lobby their MP. We're not going to fix this with individual contributions. We need systemic government-level change - shut down coal-fired power plants, outlaw internal combustion engines, stop subsidising fossil fuels, support renewables.
I heard a story recently about a logistics company that was using diesel-powered vehicles to move stuf around its sites. Diesel used to be really cheap as it was government subsidised, so the system worked fine for them. Then the government removed the subsidy, so the company looked around and found a perfectly good electric alternative and swapped straight over. They could have done so years ago, but there was no incentive. And that's across the board - people and companies, with some exceptions, will just continue to do what they've always done because there's no incentive to change. You need governement regulation to force people's hands. Yes, there may be some economic or other hardship but it will pale in comparison to the economic and other hardship that's coming our way if we don't fix this problem soon - and I mean very, very soon.
Look around you and see the chaos that climate change is already wreaking - that's with not much more than a degree's change in average global temperature. We're currently pretty much locked into at least another degree, even if we drastically change our behaviour. If we don't, all bets are off - 3, 4, 5, 6 degrees? We're looking at vast swathes of the planet being actually unliveable and certainly far more being unfarmable. The Amazon will turn into savannah (we may already be locked into that happening), the Great Barrier Reef will be effectively gone, along with pretty much every other tropical reef in the ocean. No more penguins, no more puffins, no more polar bears, no more pandas...