If asked, I tend to direct people towards the following books:
Note: you need both the student manual (which most people don't know exists) and The Art Of Electronics.
To cover the maths background required, I recommend:
They are not cheap but worth it.
Oh and a calculator. Any old cheap scientific (Casio/TI/HP) will do as long as it doesn't make errors.
The big problem for me was the maths initially. It doesn't take long before you hit a brick wall at the age of 12. My 10 year old daughter is learning algebra and programming (in python!) though at school so things are looking up.