Came across this fantastic list of Mental Models put forth by Gabriel Weinberg. He has organized them into useful sections. Do click and spend +3 minutes scanning them. Consider a bookmark-and-return approach if you don't have 32 minutes to read them now. 

Some of these models are used regularly by many of us:
Leverage - “The force amplification achieved by using a tool, mechanical device or machine system.”

Others are really good to recall and wonder how to put to work:
Hanlon’s Razor - “Never attribute to malice that which is adequately explained by carelessness.”
Pygmalion Effect - “The phenomenon whereby higher expectations lead to an increase in performance.” 

Some may provoke you to approach a current issue differently:
Power Law - “A functional relationship between two quantities, where a relative change in one quantity results in a proportional relative change in the other quantity, independent of the initial size of those quantities: one quantity varies as a power of another.”
The Third Story - “The Third Story is one an impartial observer, such as a mediator, would tell; it’s a version of events both sides can agree on.”
Forcing Function - “A forcing function is any task, activity or event that forces you to take action and produce a result.”
Luck Surface Area - “When you do something you’re excited about you will naturally pull others into your orbit. And the more people with whom you share your passion, the more who will be pulled into your orbit.”

Enjoy the list. Which one can you put to work today to make a project or relationship you're working on better? Which one is for next week? Link.