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Although it's a bit simplistic, I found this book really helped lay the overall conceptual framework for Calculus pretty well. Calculus Made Easy

And since the original is so old, you can get the free pdf of one of the second edition. The newer version modernizes the language and provide more examples but you can't beat free! Project Gutenberg link

My favorite single-variable calculus text is "Calculus" by Spivak.

I would say that readers should have some experience with computational single-variable calculus (i.e. "What is a derivative intuitively?", "How do you compute derivatives of polynomials?"), but after that Spivak is the perfect introduction to calculus for someone who perhaps wants to go on to study mathematics.

Edit: By the way, books published by CreateSpace are typically really bad (they are publishing books that are in the public domain). A better version of Calculus Made Easy would probably be https://www.amazon.com/Calculus-Made-Easy-Silvanus-Thompson/dp/0312185480/.

What is your opinion of Calculus, 4th Edition by Michael Spivak? I'm going back to school to complete my degree in math, and I want to refresh and master calculus in order to better handle advanced classes. I've taken calculus classes on derivatives, integrals, and multivariable calc, but I've taken a long break. I have Essential Calculus: Early Trancendentals, 1st edition by James Stewart, but I've heard Spivak's book is one of the best.