A strong line can make a photograph feel organised, but it can also organise the eye towards the wrong thing. A railing running neatly into a bright bin is still a railing running into a bright bin. I start with the subject and then ask whether the rest of the frame helps someone notice it.
Decide what the photograph is about
Before worrying about diagonals or symmetry, describe the picture in one short sentence. It might be a person waiting at the end of a platform, the curve of a footpath or the repeated shape of a building. That sentence gives you something concrete to judge the composition against.
If the line itself is the subject, that is fine. An abstract staircase does not need a person added merely to satisfy a rule. What matters is whether the image makes that choice clear. Several competing subjects often need a change of position rather than another compositional trick.
Follow the line all the way through
I trace a likely route from the edge of the frame to its end. A kerb might enter at the bottom, bend through the middle and disappear behind a wall. Check each stage. Does a parked vehicle interrupt the route? Does the line join the subject cleanly, or appear to grow out of their head?
Look beyond obvious roads and fences. A row of light patches, repeated windows or the direction people are looking can create a route too. You do not need to identify every line in the scene. Pick the one that contributes most and simplify around it.
Move before making a tighter crop
A small sideways step changes the relationship between nearby and distant objects. Raising or lowering the camera can separate two lines that previously crossed. I would try those adjustments before assuming that zooming in will solve the problem: magnifying a muddled arrangement usually preserves the muddle.
For a simple exercise, photograph a path from three safe positions: straight on, a little to one side and lower down. Keep the intended destination in the picture. Compare how much space each version gives the subject, and which feels easiest to read at thumbnail size.
Check the edges and the brightest patch
Lines are only one influence on attention. A pale sky, bright sign or cropped face may pull much harder than a subtle pavement edge. Cover that distraction with your hand while reviewing the image. If the picture suddenly works, the problem probably needs an adjustment to the frame or exposure rather than stronger sharpening.
Check the four corners as well. A line that almost meets a corner can feel accidental; one that enters decisively can feel more settled. Neither arrangement is automatically correct. Make the choice deliberately, especially where a strong edge leaves the picture before reaching anything useful.
Use a quick review question
Show the image briefly to someone without explaining it and ask what they noticed first. If their answer repeatedly differs from your intended subject, that is useful evidence. You can keep the ambiguity when it serves the photograph, or change the composition when it does not.
I would rather have a quiet line supporting an interesting subject than a technically tidy diagonal doing all the work. Once the route is clear, consider how the foreground and distance contribute. A photograph needs somewhere worth arriving at.