See if you can get access to a library of electronics magazines. As I was learning about electronics, I started building up a collection of "Electronics Australia" and "Silicon Chip" magazines. Even if you don't build the projects, the articles usually have good descriptions of how the circuits work, and there are often articles on various aspects of theory as well.
Start off by building up some of the designs as published. This won't necessarily teach you very much at first. But, like Dave said, if the circuits don't work, you are lucky! - you will have the opportunity to learn some troubleshooting skills. Once you are on top of this, you can try modifying the designs to do something different, or interfacing two circuits together. I found there was a fairly steep learning curve at this point, but you will get better at it over time. You can start off fairly simple, such as replacing a switch in one circuit with a relay controlled by another circuit - this is generally a fairly inelegant way of doing things, but it will get you started.
Over time, you can build up a substantial library of "building blocks" that are used in various published designs. Then, when you want to design your own circuit, you can copy these blocks out of the different designs into your own circuit. You will probably find that a bit of trial and error is required at this stage, and it would be a good idea to build the circuit up on a breadboard before you make a PCB. This way you can optimise the circuit for your particular application. After a while, you will be able (mostly) to go straight from a circuit to a working PCB. You will probably find the size of the circuit sections you are using is getting smaller, and you are using many more of them in your designs. If you find that the building blocks have shrunk down to individual components, then I think you can consider yourself capable of designing circuits from scratch!