I come from a country with a somewhat dubious stance on the environment.
My native Bahamas has stringent laws in place with vicious penalties you'd need to sell a major organ to deal with in-place to protect our oceans and most of the life within it, but I only know a handful of people who give a hoot in hell about their carbon footprint, never mind knowing just what a carbon footprint is.
Most of the places I've lived since leaving have had a similarly ambiguous policy in regards to carbon footprint management (Panama, Thailand, Florida) but it wasn't until coming to Washington state that I found myself woefully unprepared and unenlightened to really come to grips with lessening my carbon footprint. A very green conscious city threw me for a terrible learning curve upon my initial arrival, but now nearly a year later I'm as savvy and anti-carbon-footprint as people who have been doing it their whole life (Or I'd like to think I am). So for those others like me who grew up either not knowing or not having the facilities to be carbon aware, some wisdom on some simple lifestyle changes you can make to reduce your carbon footprint.
There are few things I love more than going to the food store and filling up my fridge and cabinets. It's also a bonus to do so while not having to worry about the vague threat of exotic food poisoning, but I digress. Suffice it to say grocery shopping is a guilty pleasure, but only when they started charging me for plastic grocery bags did I start carrying reusable bags on a regular basis. Then I saw the facts and became grateful for being forced to change; It's estimated that 100 billion plastic grocery bags are used every year in the United States, which averages out to 319 plastic bags per person going by 2012 population statistics. The grand total all of humanity uses in a year? One trillion. Those are some evil numbers given how it takes around a thousand years for plastic bags to degrade. Yes friend you read that right, you and I will be long dead with our skeletons stuck in a museum somewhere before those bags work themselves out of the environment. Do your grandchildren and theirs a favor: switch from plastics bags and keep a good deal of trash out of the environment.
Not owning a car is another relatively new experience for me. Ever since I got a driver's license I've have always had a personal mode of transportation whether I needed to go to work, school, or the beach for a late night, half drunk nude walk with pleasurable company of the female persuasion. That first changed when I moved to Panama, where I lived on an island so small everything vital was only a fifteen minute walk away, and then when I moved to Washington when I was too poor to afford a car and all the expenses that went with it. I've since learned that the average 10 mile round-trip commute 5 days a week for a year uses 124 gallons of gas and puts out a whopping 1.3 tons of CO2 a year. If you've got a mid-size car. Now stop and think about how far you have to commute and wonder at what the numbers must be if it's above 10 miles for the better part of your lifetime. Terrible, terrible, I know. Now obviously not everyone can bike or walk into work, so for those who still want to be environmentally savvy public transportation like the bus, train/subway or ferry are viable alternatives. If those options are out of your ability you can always carpool. Failing all else try and own a fuel efficient car, keep your tires properly maintained and avoid sudden acceleration/deceleration so as to cut down on gas consumption.
If you're not like me you probably work out on a semi-frequent basis (I don't at all). It might be going to the gym a few nights out of the week, it might be jogging for a little while daily, play some kind of team sport. Whatever it is you probably do something physical, and you've probably bought a plastic water bottle from a convenience store to drink along the way, and dropping that habit is probably one of the better ideas on this list. I've fished my share of plastic water bottles out of the ocean in my time, and it's only a small amount compared to the 1500 bottles that get used every second in the USA. That totals up to around 50 billion per year and of that only 20% are recycled. The rest end up either in landfills or in the ocean, and unfortunately the ocean isn't full of people like me who fish the bottles out of the water. The greater tragedy however is that lots of animal life, particularly marine life, often mistake plastic water bottles and pieces of plastic water bottles as food, a mistake which not only often costs them their lives but turns them into swimming toxin farms that can end up sending people to the hospital. Do the environment a favor and buy a reusable bottle no matter how often you do or don't need a water bottle.