There are always more recommendations that can be made, but the subreddit's booklist provides a great starting point with several options for you to look into.

I'm a little late to the party on this one, but thought i would add a few recommendations of my own.

Freedom National is an excellent look at the evolution of anti-slavery politics both before and during the war.

Apostles of Disunion is an interesting look at a part of the secession crisis that most people don't even known existed. The secession commissioners sent by the first group of states to secede to the rest of the slave states to try and convince them to secede as well. Does a good job of letting the Confederates themselves tell you why the seceded (hint, it was about slavery).

The best one volume introductions to many periods of American history are the Oxford History of the United States for that time. The Battle Cry of Freedom on the Civil War and its lead up by James McPherson holds up very, very well. The Glorious Cause on the American Revolution is also good, and is a standard complement to Gordon Wood’s The Radicalism of the American Revolution.

In addition, I recommend a general history of the USA such as Give Me Liberty by Eric Foner; the sections on the American Revolution and Civil War are very good/accessible, and they are designed with surrounding sections (on settlement, the early state, commercialization, Antebellum nationalism, etc.) which will help give you additional context on the big events.

Good luck! If you have any questions/more specific book requests, my DMs are open

The already-linked booklist is a good reference, but if you're relatively new to Civil War history I can't recommend Battle Cry of Freedom enough. Despite being one volume, it does a great job of covering all the major areas and even manages to touch on some traditionally-underserved subjects. If nothing else, it will give you a good jumping-off point to find out what you want to learn more about.