If a class has a destructor that releases a resource, what else must you consider?

Copy semantics, the Rule of Three/Five. If your class owns a resource and frees it in the destructor, the compiler-generated copy constructor and copy assignment do a shallow copy of the members, so two objects end up owning the same resource and both destructors release it, a double-free or double-release. You have three options: implement the copy constructor and copy assignment to do a deep copy or proper ownership transfer (Rule of Three; add move operations for Rule of Five), delete them (Class(const Class&) = delete;) to forbid copying, or, best, design so you don't manage a raw resource directly: hold it in a member type that already cleans up after itself, so you need no special functions at all (the Rule of Zero). On embedded, deleting copies on a hardware-owning class (you can't have two objects driving the same UART) is often the right, intent-revealing choice.