Measure each straight run
Record each straight section separately in metres. This makes it easier to identify corners and changes of direction.
Mark corners and endings
Note where each run starts, finishes and changes direction because these details influence the post arrangement.
Record gates
Measure the intended gate position and think about access width and opening direction before finalising the layout.
Check height requirements
Record the intended fence height and note any changes in ground level that could affect the finished appearance.
Existing concrete posts need extra care
For retrofit projects, measure relevant post-to-post dimensions rather than assuming every bay is identical.