I look for balls, it has become a sort of hobby for me. I don't go out of my way when playing with others or when the course is busy, I will go late in the day and pay to play the course knowing I'll only get a partial game in so I can look in difficult places for balls. I do this once in a while when working late driving past a course I know pretty well.
My record in one day is 520 balls.
I have specific areas on specific courses that I know where to look. Some advantages to this are, I've gotten to know the characteristics of several different types of balls and, I have lots of expendable balls to practice with when I'm playing alone on an empty course. I give alot of them back practicing off the tee.
I started playing last summer so my game is a work in progress but I've reached the point where I like to play with new balls when playing with a group when I'm keeping score. I prefer the longer less spin balls because I can't effectively stop balls on the greens yet so I like to hit them as far as I can with my driver. I play with rocket balls or e6s right now.
Incidentally, I have over 1300 balls in my garage last count that's after giving hundreds away to friends and relosing them on the course.