Data collection steps:
Mount camera on the vehicle (Camera direction should at least be partially facing the front or back of the vehicle).
Capture images in such a way that at least 3 equidistant straight lane boundaries are visible or can be labelled.
Capture at least 10 images that satisfy the above condition for better accuracy (More the number of images, better the accuracy)
Try to avoid scenarios where the lane boundaries are curved and not in a straight line.