Midair is quite often impossible to prevent.
I have been lucky at least three times, while training in busy practice area.
Later I started avoiding practice area because of that reason.
One of my friends, who had the best eyesight and was the best in spotting traffic, died of midair collision. Eyes are not very good equipment. Traffic advisory type of equipment is getting cheaper. May be it is wise to invest around 800 usd to enhance your chances to see other aircraft.