In most cases, equanimity increasing is a result of morale increasing. Any time morale increases there is also a chance equanimity will increase.
Humans in this regard have a large benefit, as they can meditate to quickly increase their equanimity and morale directly.
Performing tasks with successful outcomes, such as crafting, will increase morale and therefore have a knock-on effect to equanimity. Performing tasks that are your characters preferred activities will improve this increase.