iZotope provides some free guides, that are actually 99% generic, and only use their products to illustrate concepts and processes in an unobtrusive way. They also have some amusing, but tasteful, one-liners along the way.
If you want to set up your recording space without relying on expensive measuring equipment, and in a way that increases your discriminatory ability, as well as get many really useful recording and mixing techniques, I wholeheartedly recommend Mixing With Your Mind, by Michael ‘Stav’ Stavrou. Three of his techniques were direct enablers for our recordings (particular mic placement [p109] and pattern [p43]), and mixing (dynamic vocal reverb [p171]). The book if so full of gems, that it is easy to miss many points.