My advice on improving is this; know your music theory and study harmony. I decided to stop playing lead for a while and just focus only on rythm and harmony and it opened up my eyes to a whole load of stuff. Now i can hear chord changes and i understand what notes are good over what.
For example lets take a simple C G F progession. You can simply stick to using the Cmaj scale, but then for more complex phrasing you can use teh Fmixo (?) and G lydian (?) scales to creat a more interesting sound.
Anyway thats what i do and it find that it helps.