Many near-perfect landscape photos are let down by a slightly wonky horizon – and it’s such an easy problem to fix, either at the time of shooting or afterwards in Photoshop or Lightroom. The Transform/Geometry Panel (confusingly named differently in Camera Raw/Lightroom Classic/Lightroom CC) offers several handy auto fixes for levelling out horizons (try the Level button) and fixing converging verticals (try Auto or Full). If these don’t do the trick, there’s also the Guided Uptight command, which lets you plot lines through the scene to snap parts of the image to the horizontal or vertical axes.