Several things. Level is important. But this time I watched the video 3 times first. I think the single biggest mistake I made was I thought the instructions said to wait 30 seconds after applying the liquid. the video says 80 seconds, so to be sure, I waited 90. Also, make sure you know which is the top and which is the bottom of the liquid container. I messed that one up too. The other thing I would do differently is make sure I really wipe down the sides good prior to the final cure. I didn't this time and it took a while to remove the excess on the left side. If it continues to hold up well, I'll buy another just to store it. I had gone a month without protection and with nothing else in my pocket, i noticed all kinds of really small scratches....