Unstring your bow when you're not using it. That is, unless your bow is fiberglass. If you have a fiberglass bow, it doesn't hurt it to leave it strung all the time. But if your bow uses natural materials on the back and belly, you need to unstring it when it's not in use. The reason is because natural materials deteriorate over time. When your bow is strung, the belly is under compression, and over time that compression will make the bow weaker and weaker, and it will take on set. If you leave it strung, you're reducing the life of your bow.
Can you leave a recurve bow strung?
Now, you might wonder when exactly you need to unstring it. For example, say you're at a 3D shoot, and you take a break for an hour before you shoot another round. Do you need to unstring it if you're going to shoot it again in an hour?
That's a judgment call. You can leave the bow strung all day if you want. Keep in mind that every time you string or unstring your bow, you're taking a little risk. It's like accidents. You know how they say most car accidents happen near home? Well, most bow failures happen while stringing or unstringing. So if you're going to shoot your bow off and on during the day, just leave it strung. But, you know, if you're going to go a whole five hours without shooting it, then unstring it.
Replace your string if it looks ratty. If your string looks old and worn, replace it. Strings are cheap, especially if you make your own. It's better to replace the string than to replace your bow because it broke because the string broke. If you have any doubts at all about the condition of your string, just replace it. Keep some wax on it, too, because that'll make it last longer. Wax not only holds the string together, but it also protects it from moisture.
Don't store your bow by resting it on its tip and leaning it in a corner. For that matter, don't stick the tip on the ground and lean on the bow as if it were a walking stick. Those tips are absolutely necessary for the bow to function because without the tips, it won't hold a string. So you don't want to rest the bow on its tip because that'll wear the tips out faster. Also, if you're like a lot of people, when you lean one thing in a corner, next thing you know, you're also leaning your gun, your broom, and all kinds of other things in the corner. If they lean against your bow wrong, you might break your tip off.
Lastly, if you store your bow for long periods of time, put it in a bow sock. A bow sock will protect the bow from dust, cat hair, and dings from being moved around, piled on top of stuff, or buried in closet debris. When we say "long periods of time," we are talking about more than a year. But who would leave a bow sitting around for more than a year without shooting it? Yeah, that's extreme. That's why this rule is at the bottom of the list.