Watch the E7, A7 & B7 Chords online guitar lesson by TrueFire from Play Blues Guitar 1: Quick-Start for Beginners
Playing songs is what we all want to do! So putting together various chords and feels in song structures will help you build both a technique and song repertoire. This E7, A7, and B7 blues will be used many times in your career so get it down and have some fun with it!
Once again go slowly until you get the changes down. Always look for problem areas and work on those spots. For example if you have trouble switching from the A7 back to the E7, rather than continuing to play through the whole chord progression, just stop and work on that switch. Drill down on the problem areas whenever you can.