A big problem when learning art is finding books about the real basic stuff, not whatever "fundamental" or pony someone wants to talk about.
Without an art instructor you easily end up jumping into advanced topics before you have actually learned the basics of drawing.
E.g. perspective light&shadow, or the human figure are all advanced topics. Interesting and useful to read, but no point working on them seriously if you haven't learned the more basic stuff.
Basic skills are actually:
- Eyeing/measuring with your eyes
- drawing (construction) lines freehand
- shading with pencil, pen, and in color
- direct drawing/painting
Except for direct drawing/painting you need all these skills for drawing from imagination, too.
As books for the first steps, I will just recommend
http://www.gutenberg.org/files/30325/30325-h/30325-h.htm
Which teaches pen, pencil and (water)color basics. This also includes things like outline and shading.
And
https://archive.org/details/lessonsonart00hardgoog
Which teaches you to accurately measure with your eyes and accurately place construction lines and complex objects freehand on your paper. The second is also in print, and that version is IMHO better because more straightforward.
Both books are outdated in some tools, so you should replace the tools there with modern tools as needed. Dip pens with fountain pens for drawing, pigments with gouache tubes. As paper copy paper is good enough for pen/pencil drawings.
If you are still in school, you can join some art club under the art teacher and spent your afterschool time drawing busts, still lives, and so on under their instructions. But if the instructor isn't serious, you may as well just stay home or go somewhere else. Going to lessons for advanced topics like drawing humans or painting with oils and acryl is pointless as a beginner, so don't waste money on that. Refine your skills first before paying for people to stand model or for expensive paints you aren't capable of using and which go bad in a few months.
Aside of the above, you still need to read all the books specific to your goals. Neither replaces the other. But if you want artistic good results, you should learn the basic stuff above first.