rest arm

I am starting to practice my rest arm at home doing the push motion 100 times with the cue rested on the back of my dining chair starting last night.
The rest shot is like the regular shot whereas one needs to train one's muscle to shot straight.
What I do is I try to hinge my elbow while keeping my wrist loose and push the cue straight, 100 times. I did that last night and just finished it this morning. Hopefully this would help. if I keep this up.
D is so bad with the rest and he never bothers to practice it. A lot of players are able to run more points because they could play that one tough shot with the rest. It is a very important shot.