I've never seen the book "Practical Electronics For Inventors" but I can comment on "The Art of Electronics". I started out in electronics at the age of 7 with a 300 in 1 kit but got very fed up that I could only follow the instructions and couldn't design my own things or modify those that were there. It did give me a grounding in reading schematics though as the harder projects in the kit did not give construction information. If I remember correctly, everything was built with wires between springs on a board.
I then bought a few Tandy / Radioshack books by Forest Mimms who is a great author for clear explanaitions of how components work and basic circuit advice. I seem to remember the first manual was "Getting Started in Electronics" which I lent to a teacher and never saw again. I'm not sure if it is still available.
"The Art of Electronics" has been with me since age 12, and while I read it cover to cover then, I only understood around half of the content as it does require a good grounding in high school maths (integration, differentiation, a little fourier series, algebra). I have to say it was still a very useful book and I have used it throughout my time at University and in employment as an electronics engineer.
Another good book, although it is out of print at the moment is "Analogue Circuit Design: a First Course" by H Martin Reekie who was one of my favourite lecturers. It covers a lot of transistor and opamp theory in simple terms and is intended as a 1st / 2nd year university text. Martin also includes a considerable number of rules of thumb that saves on pages of maths in many situations. I know a number of hobbyists who use this book
Below here are university level analogue design books...........
If you want to advance further, you may want to consider D.A. Neamen; "Electronic Circuit Analysis & Design" as a good grounding in the circuit analysis performed to optimise analogue circuits. D.I. Crecraft, D.A. Gorham, J.J. Sparkes; "Electronics" also covers some of this material in a more general level.
Finally (and hoping not to scare you), if you are really keen, SPICE analysis can be handy to simulate circuits for you. Its available in a number of forms as both free and commercial software. Berkeley Spice and PSpice are what to look for. This should probably only be considered if you are very keen to design your own amplifier topologies or see the effects of making component changes. It can be particularly useful for looking at the frequency response of circuits. A. Vladimirescu; "The SPICE Book" and P.E. Allen, D.R. Holberg; "CMOS Analog Circuit Design" may be useful as a manual and reference. The other possibility for more graphical (and easy to use simulation) is software such as "Electronics Workbench". It's drag and drop components and runs a similar engine to spice behind it.