Actually, there is no safe way to crack your knuckles. That’s the truth. Sorry.
It’s basically just a bad habit. It may feel as though it provides comfort or a release of some kind, and that may be true for the moment, but over time it can lead to problems in the future, such as weakness in your hands. Have you ever seen a grandparent, or someone younger, having a difficult time buttoning a button or holding on to an object? It may not seem like a concern at this moment, but your health later in life is affected by what you are doing now. What seems to be a minor thing today—What difference does it make?—can lead to discomfort, pain, or even take away your ability to do some basic things when you are older, such as tie your shoes, use a keyboard or pencil or battlestick, or hold your own fork while you eat.
If reading this makes you want to crack your knuckles, sorry about that. If you have that urge, just tell yourself that you are bigger than it. You are in control. Don’t give in. Find something else to do to get your mind off the matter—after you finish reading this, of course. You’ve probably heard that I’m a fidgetarian and sometimes just have the urge to move around restlessly or impatiently. I realize it is a habit to crack my knuckles and if I’m aware of it, I will do it less. Mostly. At least I’m trying.
The last comment about this is that if you have cracked your knuckles a few times already, it doesn’t mean that you need to be afraid of the future condition of your hands. Stop now and prevent the bad habit from taking over. Done.