Strunk and White would seem more immediately useful to the OP.
The Art of War is a good book. My opinion are that these are what I call universal principles. These principles can be scaled up or down based on the environment in which you find yourself. I often relate it back to my martial arts training as it too translates to life. Budo is bu (Warrior) and do (way) is life long training, but the physical part of the training also enlightens one on life and the interactions of everything. Martial training emulates life. Same goes with The Art of War.
Another great book that I think is beneficial to read is "The Book of Five Rings", written by the master swordsman Miyamoto Musashi. I believe it is freely available in digital form. Although it is written from a martial sense, it is applicable to many of life's challenges.
I would add that the Art of War is not just for someone in a leadership role. It is applicable to life. Think of it more on a granular level. Life is a series of struggles, it is a series of choices and consequences. There is always an exchange of energy, whether it is a decision to make, a conversation with someone or many (happy, sad, violent, or indifferent), or a business deal. It isn't necessarily a confrontation and it doesn't have to be negative and can be positive. But it is about achieving your goal through making the most efficient choices to affect the outcome you want to achieve.
In the book, he is talking about armies and strategies, but if you look closely, it all can be applied whether it is one person, two people, twenty, or thousands.
I would be interested in seeing other's interpretation of the Art of War's principles.
I think the eBook is generally available for free on websites/apps/etc. so its well worth taking a look at.