How to learn to read music

Hello, I studied classical guitar for some years, and here is what works for me:
First of all reading is one thing, playing by sight is another.

As for reading, here are some tips:-practice rythm separately: try to beat rythm patterns. If you don't have any book, search the web, or create your own, always trying to keep them simple.
-practice reading notes names (without singing). To achieve this you will find it easier to memorize where they lie in the partition.

As for playing, the issue of placing the notes on the guitar does not have a straight forward procedure. Here is for me the best procedure:

1-Try to understand the musical idea. If you don´t know it, try to sing, or play only the main melody.

2-Isolate the bit that makes sense alone.

3-Try to place it on the guitar. As several frets are possible, you should try them all and choose what best fits you. For me, it is oftem more a question of "playability", than of "what sounds better"
I've seen lots of fingerings and TABs that suggest places that don't work for me, or simply are wrong. So you shoulçd see them as suggestions, not as "the right way to play the notes"
Often you will choose a position and years later, you go back to that music and find it inadequate, thus changing it.
It happens a lot and it's part of our never ending learning process.

Good luck