Instead of buying plastic water bottles when you travel, buy a water bottle and refill it. When you get coffee, get it in a “for here” cup that the coffee shop can wash and reuse, or bring your coffee cup if you want to take it to go. Apply this concept to anything you buy that could use a reusable container instead of a disposable one. This will help save on resources to produce those single-use containers.
Here are more examples: Use tin tupperware containers to take your lunch to go instead of aluminium wrap or paper bags. Refill your soap dispensers instead of buying new ones. When you picnic or BBQ, use reusable plates and silverware.