The clue is in the name: at a stop junction you must stop before the line (it’s the law). The common mistake at stop junctions is treat it the same as a give way junction. The reason for doing this tends to come down to one of these two things:
Failing to identify it as a stop junction
Failing to recognise the difference between stopping and almost stopping
HOW TO IDENTIFY A STOP JUNCTION
STOPPING AND ALMOST STOPPING
If you are eager to get away at the junction, it can be a fine line. The trick here is to take your time. It is a stop junction for a reason. Don’t just stop behind the line; stop and take a moment. Count to three or put the handbrake on for a second. Anything to make sure that you absolutely, definitely have stopped.
Once you have stopped, you can then treat the junctions as if it is a give way. If your view is obscured, you should edge slowly forwards while alternately looking left, right and (if necessary) ahead. Move off when you can do so without affecting other road users.