I saw the video the CDC suggested for getting a closer fit using a surgical mask. I had a tough time following how to tie the knot in the loops. Either the demonstrator went too fast or I was too slow (probably the latter.) I found a couple of videos on slip knots and crochet knots (another name for slip knot, evidently). There are probably dozens of YouTubes on how to do the Knot and Tuck.
Since the toughest part of the Knot and Tuck method is tying and adjusting the knot to hug the edge of the mask as closely as possible, I practiced a little. See what you think of the slip knot and tuck in my YouTube video below. Using a slip knot allows you to easily move the knot closer to the side of the mask, allowing a tighter fit. Tucking also helps. It also helps prevent my glasses from fogging up. It’ll never be perfect but it’s better than letting the sides flop open.