Just keep playing a song by ear and try to use your ear most of the time.. try to add bits and pieces to the original song that you might or would like to play on it.. this improves your improvisation also. but most of all you would know what the chord patterns are like in most of the songs. you would even know what tuning is the guitar on to play that stuff etc etc.. if you try to add solos or fills on a song thats probabl one of the best ways for improvisation and everything else.. I know its a little out of topic and all I think but hey I guess it would help you guys..
Like I did some fills and added a solo on a brand new song called "hey kid" by Matt Willis which originally had no guitar solos so I felt it deserved one and I gave one.. good thing is people like it more than the original song enjoy