How can we protect the environment?

First and foremost, individuals matter. In fact, individuals are the only way we're going to be able to achieve anything related to environmental conservation.

1. Source reduction- This is way more effective than anything anyone else will suggest. Yes, recycling is awesome (and reusing even better), but assessing your needs and avoiding excess consumption is the most environmentally sound way to go about buying something.
2. Invest in reusable products- Get a nice, BPA free water bottle. Find a really sturdy mechanical pencil- my metal one has lasted me about three years now.
3. Grow your own food- It's quite common in Poland (and much of eastern Europe) to grow your own vegetables and can them for the winter, but since I moved to the United States, I've noticed it's less common here. I don't know if that's a cultural thing, but I find it very interesting!
4. Invest in local business- By spending your money wisely, not only are you providing economic stimulus for the community in which you live, but you're also preventing whatever products/goods you buy from being shipped halfway across the globe. Eat local foods and buy local things!
5. Make as much of your own stuff as possible- Make your own clothes (maybe a scarf for the winter or something if you're not that fabric-savvy), make your own toothpaste, soap, shampoo, etc. from organic, locally sought materials, which reduces carbon emissions and the use of industrial waste from many huge companies that just pump sludge into the ocean or into landfills. Gross.
6. Use cleaner technology/transportation- If you live in a city, you might be able to walk or ride a bike to work. If not, public transportation is better than driving your own car. If you do drive your own car (of course, that's often unavoidable) try to keep the driving to a minimum and buy greener cars. Do your research!
7. Don't waste water- Turn off the water when you brush your teeth or shampoo your hair. Only fill up a cup with as much as you're going to reasonably drink. If you carry around a water bottle, and you have water left at the end of the day that you're not going to drink, water your plants- just don't mindlessly dump it down the drain when you can use it for something useful.
8. Eat less meat, more plants- Eating plants uses much less water than eating animals (think of all the water needed to grow the plants that feed the animal) and is often healthier. This also decreases the rate of forest clearing for animal agriculture (sorry I don't know the English name for it- I don't think that's the actual name) and significantly decreases the amount of methane that enters the atmosphere.
9. Keep up with environmental issues- Science is a field that is constantly changing. New developments on the environment are an everyday occurrence as this is one of science's defining characteristics. Have proper environmental intellect!
10. Last, and most importantly, educate- You seem like the kind of person who believes that our world is in deep environmental trouble (why else would you be asking this question). I'm very happy that people are asking this question, and it's important that more and more people are asking this same question- "What can I do to help?" Spread the word, be excited and passionate about our natural world, preserve biodiversity, and never stop doing your part! Convince others that individuals matter!