Don't expect to fire off shots with a brand-new, unfamiliar camera and still achieve travel photo greatness. Likewise, you can't conjure wonderful pictures if you're struggling with basic rules of composition. Nail down the fundamentals while you're still at home.
It starts by understanding your equipment. Whether you have a pro-grade SLR (single lens reflex) camera and a suitcase full of lenses or a simple point-and-shoot camera, you won't get far unless you know your gear inside and out. At the very least, understand how to control the settings for aperture, shutter speed and ISO setting, and know how to quickly switch from various modes depending on your subject and light conditions.
You'll also need to understand the importance of composition. If you aren't already, you'll need to be familiar with terms like the Rule of Thirds or the Golden Spiral. In short, these terms guide you to compose your photos with the subject off-center. The slight sense of imbalance tends to draw the human eye and make images more fascinating, no matter the subject.
And whatever subject you choose, fill your viewfinder. That is, get close enough to your subject that you aren't including a lot of extraneous objects that clutter the scene. Generally, simpler compositions that portray only vital elements are the most striking. You may have to choose an awkward angle or get very close to your subject in order to pull of this kind of reductionism, but more often than not your efforts will pay off.
Quality of light is also critical. Regardless of what you're shooting, the angle, tone and color of light in your image will affect its emotional quality. For example, a city street at noon might look drab or stark. At night, that same street may be awash in mysterious light that beckons hauntingly to your camera's lens. As a quick and dirty rule, though, the first hour after sunrise and before sunset frequently offers some of the most interesting and flattering light each day.