1. C: A Reference Manual, by Harbison and Steele.
2. The C Puzzle Book, by Alan Fueur.
Harbison and Steele has much better explanations than K&R.
The Fueur book taught me a lot about C declarations. Declarations are that part of C language that is them most unnecessarily difficult.
You asked about a slightly different question, best practices. But in the real world you'll run into a lot of code that practices below that level.
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