Here's a cool tip on soloing over Dom 7 chords to give your licks added character! Lets say your soloing over a A7 chord. Most blues, rock guys would play your standard A minor Pentatonic Scale, Blues Pentatonic Scale or the Mixolydian mode or 5th mode in the key of C.
If your into jazz horn players like John Coltrane,Miles Davis etc., this will give your solo's that kind of sound. For soloing over a Dom 7 chords like A7 for example, play the B flat minor pentatonic scale. I know your thinking that's out of key right?
Well if you phrase your licks wrong and hit the wrong notes on the downbeat it will sound bad. The key is to do it in moderation with the common notes in a minor pentatonic scale. It takes some practice but when you get it down people will take notice.