One way of learning quickly is to obtain some material that offers instruction in building electronic projects as you go, while teaching the theory behind it, which would be based on the area of electronics you wish to persue.
Because there are so many areas that come under the umbrella of electronics it is really important to obtain a very good background in basic Electricity, which essentially is AC & DC theory and how individual components are affected by each.
Once you have this you can virtually go into any area of electronics/electricity and get up to speed faster.
Because, I assume you are not making this a life career, the fastest way maybe the first method I mentioned, together with a good book on basic AC/DC theory and one hopefully, complement the other.
There is also a wealth of information here on the w.w.web.
If you get something laid out in lesson fashion, make sure you are confidant you have it, before going to the next step.