Watch the Dominant Soloing 1: 8 online guitar lesson by Brad Carlton from Bluesology 1

OK, we're almost ready to solo over the entire blues form. First, we'll talk about the last 4 bar phrase (V7-IV7-I7-V7). Once again we'll talk about targeting the roots of the chords.
Besides making good pitch choices for chord changes, an improviser has to be aware of the other elements involved in building a strong solo. Rhythmic ideas, motif development, phrasing and articulation, pacing are a few concepts to consider. If you leave a little space in your solo you'll be able to listen more intensely to what you have already played and at the same time pre-hear what will follow.
Now let's dig in to the 12 bar blues.