The biggest idea to take away about potential energy is that you increase the potential energy by making a system move in the opposite direction that the conservative force is pushing or pulling on it. The gravitational force wants to pull object downward, so you increase the gravitational potential energy by moving them upward. The spring force wants to pull a mass attached to a spring back towards the equilibrium point of the spring, so you increase the elastic potential energy by pushing or pulling the mass away from equilibrium. Even when we add new types of potential energy, like the electric potential energy when we talk about the fundamental property of charge, this rule will hold. If the electric force, which is conservative, wants to pull two charges together, then you increase the electric potential energy by pulling them apart.

Similarly, when you let an object go, it will always move to decrease its potential energy if it can. Pick a rock up and let it go, it will fall back towards earth. As it does, the gravitational force does positive work and the gravitational potential energy decreases. To prevent the rock from moving to decrease its potential energy, you need to find something (a table, a shelf, a friend who is willing to hold it) that will exert a force which holds the rock in place.