. However, lack of information is not my problem. My problem is mostly picking the correct string and, sometimes, fretting the correct fret. I seem kinda confused a lot, but not on my other string instruments. Sometimes I play better by ear (watching my fingers).
There're tricks to fixing your problems that I've found useful (BTW, they are very common problems).
For fretting the right fret, when playing in first position, you can maintain your thumb (on the back of the neck) behind the same finger (the thumb can move sideways on the back of the neck but doesn't need to move up/down the neck too much). This thumb is your base and point of reference to place the fingers. Another useful thing I'd like to do is to spread out my fingers on the first 4 frets on one of the strings to get a mental image of their widths (I also play on travel guitar that is much smaller) before I start.
If you look at my videos, you can see that my thumb always stayed under nearly the same finger (in my case, it's about finger 2; middle finger) even when my hand moves up/down the neck a little bit to help my fingers reach the frets, the thumb doesn't move (because I'm always in first position).
For plucking the right strings, I use anchor my thumb on a string (or the guitar body when I need my fingers for the lowest of the strings). This allows me to know the distance I need to move my hand to cover the right strings (my hand always stay above my fingers so I don't "move" my fingers to the strings; this is a way to help with consistent tone). I do move my hand around sometimes (for tonal variations on repeats), but that was very difficult initially (over time, it became easier as I gain more experience at different distances from the bridge).
If you look closely at my videos (esp. the 2nd one where I'm a little bit more comfortable with the piece), you'll see that my thumbs is almost always anchored on a string.
I gathered those above tips from in-person and online lessons since I started classical guitar 1.5 years ago. I don't think they are talked about much in books (but I have to admit that I don't read any guitar books besides my lessons and song books).