Here is a practice track which I have done in an Indie Rock style, to show that simple things can be very effective. It is suitable for guitarists and bass players of beginning to intermediate level. The chord progression is a very common one in lots of songs, involving the chords C, G, Am and F:
To solo over the progression, first recognize that the progression is in the key of C major. So use the notes from the C major scale. One concept that you can use is to hit the first beat of every two bar group with a sustained note from the chord. That way you accentuate the harmony and sound “in control” of the progression. C chord: C, E, or G. G chord: G, B, or D. Am chord: A, C, or E. F chord: F, A, or C. To add interest, follow the strong note with some linking scale tones that lead to the next strong chordal note at the change of chord. Add interest by hitting the chordal note more than once, in different rhythms, to more strongly emphasize it. Interest and emphasis can also be added by first hitting the tone above or below the chord note, and quickly moving to the chord note. Another idea is to follow the first chord tone by another chord tone, thus doubly emphasizing the harmony.All these ideas can be heard in the following track including my solo (try to play along with me):
To practice your own solo, here is the track without the lead guitar: