Use diagonal lines to add impact to your photos, it’s easy to do and can be very effective. They can also help to draw the eye through a photo.

It’s a simple compositional trick that can imply action, add depth to your photos by suggesting perspective, and add a dynamic look and feel.

Lines exist everywhere, in the form of walls, fences, roads, buildings and telephone wires, sometimes it's just a matter of changing the camera angle or lowering or raising the camera height. Here's an image that many people would have taken from a frontal viewpoint:-

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On a beach, you can often use breaking waves or the surf to create diagonal lines, this can look especially cool if you get down and take the shot from a low angle, try to avoid dropping your camera into the sea 😉
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All of the lines in previous photos were real physical lines, but diagonal lines can also be implied for better photography composition, by positioning objects, changing camera angle or maybe even when posing people. Compare these two simple shots of some friends, in the second image their heads form an imaginary diagonal line and the pose looks better than in the first.
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Here's another couple of simple photos for comparison, which one looks better?
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