Be careful if you are going to practice emergency avoiding action turns - you could overstress the airframe on your aged PA28 / C172 as well as inducing an unwanted upchuck from your passengers.
IMHO, I suggest that you go to an aerobatic trainer to be shown how to do them properly and in an aircraft suitably certificated. Periodically repeat the exercise to keep your skills up.
In the hopefully unlikely event you have to do one for real, overstressing the airframe should and will be the last thing on your mind but I'd be reticent to risk damaging your pride and joy with practice emergency turns until you've become proficient.