When you tie your shoe laces, you're probably using a square knot [1] but with double slip. If your shoe laces often open while walking, you might be doing it wrong (granny or thief knot).
If you want to learn just one new, very convenient knot, which can be used in many situations, I recommend the Bowline [2].
It’s a great knot to get other people interested, too, because you can go “alright, so first you start in this position like any other knot, right? Then you just zwoop and done”. Tying your laces in a single fast movement really makes your nerd friends curious. It’s like a magic trick.
I, too, am a fan of the Ian’s Knot site and for at least a couple of decades. A while ago I noticed that he has posted a page through which people can donate to the site’s operation but also which details all of the income sources that have dried up.
I donated today because his site is worth supporting.
The Ian's Secure Knot is what I've used for years and the only shoelace knot my kids were taught. Trivial modification of the usual bunny ears and hardly ever comes undone.
Interesting, I actually learning the Shoelace Bow (surgeons)[1] from this site a couple years ago and it's my go to now for any shoelaces that don't lock tight or that I really need to stay tied (think running or backpacking)
If you want to learn just one new, very convenient knot, which can be used in many situations, I recommend the Bowline [2].
[1] https://www.animatedknots.com/square-knot
[2] https://www.animatedknots.com/bowline-knot