The Elements of Style

Published in 1918 and therefore antique, this reference book is still essential if you want to become a better writer.

It establishes the basics of what should and shouldn't be expressed in words, in a clear, direct and informative way.

Not all its contents are essential, but I picked up on tips and guidelines and 'I never knew that' revelations all the way through.

I recommend listening to what William Strunk Jr and E.B. White have to say and taking their wisdom on board. Many famous authors swear to the relevance of this book even today.

Think of it as a writing-standards reference manual on constant read, to help avoid obvious or glaring mistakes.