A lot of generalized forms of the right answers are usually what you will find here. Let me give you a quick run down of the cutting edge of Appropriate technology; Source, a B.S. in Appropriate technology and sustainable development. Spark notes version: efficiency is paramount. The reason renewables seem so daunting at the moment is because they required larger installations to cover our current usage which is remarkably wasteful.
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This concept extends to every aspect of human civilization's requirements to go on. The very definition of sustainable development and appropriate technology is "Technology that allows the present generation to meet their needs without jeopardizing the ability of future generations to meet theirs".
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So cutting edge technology is helping with this and one of the best ways is to support these technologies as much as possible in order to get them to market and mainstream to prove their economic viability. Lets face it, efficiency is a no brainer, do more with less. Except the bottom line is three fold instead of just one: profit. People, Planet, profit in business circles (3P's). Economy, Ecology, and Equity (humans) the 3E's in the Sustainability field. Those are the bottom lines for capitalism now, and their application will drive one hell of a future.
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So Now lets look at technologies worth supporting that are making it incredibly efficient and minimally impactful to meet our needs. In many cases without sacrificing much of the culture of plenty we have come to be accustomed.
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High performance building standards!!!!! These standards take resource efficiency like water and building materials into account as much as Electricity. USGBC and LEED is great for commercial buildings. Energy Star, NAHBGreen, Resnet HERS, and BPI for homes. Make sure you buy atleast a performance rated home by a HERS or BPI rater. NAHBGreen and EStar are usually already rated as a prereq. They are more expensive now because builders can be a slow learning curve. The materials and technology standards required to get a home or building at an amazingly low usage is actually really inexpensive once a little installer competency gets thrown in. Also if you buy the less expensive home you're likely paying the difference within a year of higher usage costs, or performance upgrades. Also Keep in mind construction wastes billions each year (or around 40% of total GHG emmissions per year U.S.) in materials wastes sent to a landfill without any requirements to divert or repurpose.
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Transportation: hydrogen is great and all but the electrolosys part has some nasty byproducts and is energy negative. Battery technology like Tesla's is more than likely going to leap frog and become standard. Not because it is particularly above par but because it is being designed as highly compatable with other systems. So when your home becomes as energy efficient as it could be the PV required is maybe an array of 4 average efficiency panels. The smaller system costs allow you to install the system to connect to a battery. Those are expensive, but if theres already a compatible one in your car then its not so painful on the pocket book. This is a great foundation and with further R&D it won't be a surprise to make batteries significantly cheaper, more energy dense, and by extension smaller.
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Agriculture; jebus is this one tough to explain. Basically our agriculture system is archaic compared to current technology in terms of resource efficiency and well being. You will read about how carbon intensive and energy intensive current agriculture is, don't listen to stats quoted that don't take into account the entire embodied energy(look it up) of a single product. To the point: GMO's are great but many act like they are the cure all that they are not (yet). GMO's assume increasingly hostile growth environment's and often treat the plant as the only defense, which is how they should but nudges out congruent technologies. A great half way is vertical aeroponic (or hydro) agriculture which utilize high yield GMO's and off maximum efficiency (60% less water and nutrients I believe). Its also an incredibly effective system for controlling and wiping out blights through rapid quarantine response. Aquaponics are AMAZING too in that to further simplify and diversify the process allowing fish to create the fertilizer while the plants clean the waste water to help breed large healthy fish for consumption. Which of course allows us to leave the nearly depleted ocean fish stocks to rebound. Support farm grown seafood, the Ocean is nearly empty trying to meet global demand. You think its expensive now, wait till there's a shortage because we didn't invest into enough fisheries and have made tuna as rare as gold which isn't far off (read your lifetime easily). As for alternatives that may make that much easier soon: Lab grown meat. Grown or 3d printed this will allow us to relieve the massive amount of land and infrastructure required to keep up with global demand for many sources of meat. The price is quickly dropping and with mainstream and better methods it will only drop. I cannot wait to try them, simply because I love to eat cows...but theyre cute and funny and I don't like the send off we give those honored sacrifices who gave their lives to be my glorious burger.
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Energy Generation: Emissionless renewables PV wind micro hydro/wave (just avoid bio-diesel Nox, is terrible for forests, plus those oils would be best producing bio plastics), fission, thorium, pebble bed reactors, and molten salt reactors to utilize our vast amounts of waste rods that contain I think 94% still fissile material.
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Materials; Concrete is actually on of if not the biggest source of CO2 emmissions in the U.S. There are alternatives being developed that sequester carbon while it cures, but I cannot find it at the moment. Either way Concrete is a one time emitter as aposed to a constant release. Deforrestation for timber demand has a long term impact while land recovers. Make sure wood products are certified from a sustainability minded organization in the U.S. preferably one that isn't associated with the timber industry. READ UP. Now as for other common products; help the industries heavily involved in recycling and repurposing with strict goals to redirect from landfills. Plastics although petrol born are incredibly useful, recyclable and overall amazing materials. It is moronic to think that so much of the stuff is littering slums, ocean heaps, and land fills when it could be repurposed to save money somewhere. There are chemical products for everything you shouldn't let get into the water supply that are bio degradable and barely less effective. The more mainstream these items like detergents, softeners, paints, glues, sealants, etc the less expensive they will become. It is utterly fantastic that those industries are growing and have the momentum they do, but this is the time to actually vote with your wallet because lack of availability is no longer an excuse.
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Community: Move to a city. Help make it a place you enjoy living. The cities of the next ten years are going to become urban playgrounds mixed with green spaces, community centers, maker and creative spaces among the staple shops, offices, warehouses, and appartments left from the last generation. No longer are cities going to be thought of simply in terms of bastions of industry and financial capital, but you will see the 3E's (3Ps) embodied in the next 20 years just from the new urbanist movement already in play. You see it in new york with the high line park, bike lanes, pedestrian space in times square and cities all over with green ways and mixed use repurposed everything. If the only complaint you have about a city is it's noisy, then I refer you back to my first paragraph about proper building performance standards and noise reducing insulation installation...if you can really hear that much I'm willing to bet you're heating bills are pretty high for that city apartment.
...I think I've covered the starter kit. NOW PAY ATTENTION. 3rd party verification is PARAMOUNT. The "green" wave is at a close and far too many ass hole companies rode it without having to lift a finger or change a thing (the term is green washing). This has left an understandable dent in the movement with consumer confidence. Make sure the certifier is truly third party for that industry. Or if they are naturally closely tied that they as a company or organization have a good reputation for integrity. A Fantastic credential for a company to have is the B Corporation Mark. I try and shop and contribute to these guys. There are other industry specific certifications but for those companies that don't fit a specific industry well or their industry doesn't have a recognition for excellence in sustainability, this is the mark to look for. I hope this is enough to get you started, I can go on for days like this so yes people I glossed somethings over, doesn't mean Im ignorant but I need some sleep.
TL;DR fuck you, this shit is important now and the next 50 years. Read the damn thing.