Watch the One Four One online guitar lesson by Jeff McErlain from 50 Eclectic Blues Licks You MUST Know
It is a very cool thing to be able to outline the chords when soloing. This is called playing "on the changes" as opposed to playing "over the changes". So by outlining the key notes of the chords of a blues you express the harmony of the progression.
This can be difficult at first but well worth the work since it adds a whole new dimension to your vocabulary and opens up new doors for improvement.