Hi and welcome. Cutting cardboard is definitely not good for the edge. I would up the strop count to at least 100. If you still requires honing get a pro to do it for now and then learn to maintain the edge first before trying to hone yourself. Pressure and angle are the main reasons beginner have trouble. For pressure use just enough to cleanly wipe the lather off and then focus on your angles and skin stretching. Good luck and if you have any questions about anything feel free to ask. Ed