I am a frequent traveler, often in developing countries that lack a solid infrastructure to process waste. I find that being a tourist just naturally comes with a lot of waste: we buy bottled water, we do a lot of shopping and receive items in plastic bags, etc.
Over the years, I've adjusted my habits to reduce my impact (e.g., I filter my own water, bring my own bottle, bring my own reusable bags, etc); however, I would LOVE to learn what other people do so I can learn new ways to reduce my impact. Any tips are appreciated!
Travel is inherently unsustainable. You can purchase carbon credits through an online website like myclimate and fund projects that reduce greenhouse gas emissions.
Another easy way to reduce waste includes traveling with your own reusable utensils and refraining from using other single-use plastics.
We take local transportation (versus private transport), which reduces traffic and pollution, or walk when practicable. We too use our own bottles and filter our water. We try to buy local products w/o packaging, refuse plastic bags/straws, and have our own reusable utensils (or eat with our hands).
First of all, don't minimize what you're already doing. You're NOT adding more disposable water bottles to the world. You're not adding to the problem of single-use plastic shopping bags. Those are important.
Another thing you may already be doing is traveling economy class. When you're packed into a plane like sardines, remember that you've cut the amount of fuel to transport yourself, compared to the comfy business or first class seats.
Beyond those, I'd encourage you to learn more about the area you are visiting. In Nepal, energy production is scarce. We found that many lodge owners only lit cooking fires a couple times a day. By ordering our breakfast the night before, we helped them maximize what they could accomplish when they did light the fire. We also carried solar panels to meet much of our electricity needs. In Cape Town, South Africa, water was the most scarce resource, so we trained ourselves to practice extreme water conservation. In all places, we brought our own bags, carried our own water - and should have carried our own utensils!