These are the four shapes I use when improvising over dominant 7 chords. Getting a handle on each one will help you know what notes to play over dominant chords. The more you practice visualizing these shapes on the fret board the easier it will be to find your way around. It’s like learning to walk. It is very slow at first, but as you practice these shapes you will start having little epiphanies along the way and at times you will really surprise yourself at how fluently you can move around the fret board.