How to improvise over a chord progression?

Question

Lets take a chord progression:

C-Am-Em-Bm in the Key of C (if that's incorrect don't hesitate to correct me). How can I do a solo or an impro avec that, do I juste take a scale like the major C scale and improvise over it? Do I have to know the C scale over the whole guitar to be able to do that?

Answer 1

Learn blues scales.  I suggest the series by Jamey Aebersold that has scales and CD's to play along with.  (Start with Vol. 1).  Anyway, to answer your question...

over the C and Am you could use the A blues scales (based on A minor).  Over the Em, use the E blues and over Bm use the B blues.  The notes are:

C (A blues) A - C - D - D# - E - G - A

A m ( A blues) A - C - D - D# - E - G - A

Em (E blues) E - G - A - A# - B - D - E

Bm (B blues) B - D - E - F - F# - A - B