Watch the Legato Exercise 4 online guitar lesson by Jeff McErlain from Beginner Blues-Rock Soloing
This may sound obvious, but make yourself as comfortable as possible when practicing. I certainly do not mean reclining on the couch! It's best to find a chair of proper height with no armrests, the chair should have a back with some lower back support. Proper posture is very important when practicing. I definitely suffer in this area as I watch myself slouch in these videos. That being said, when I practice, I have an area set aside with everything ready to go. My chair is nothing special, but it requires that I sit up.
In my classroom, some people send me videos of them sitting on the edge of their couch practicing and they wonder why they're having problems with the exercise. The couch is way too low to the ground and that pushes the guitar up too high. Bad posture will always lead to bad practice and technique.