While attending a National seminar on physical education at Choudhary Devi Lal University Sirsa, I came across a paper titled, "TOSS JUGGLING AND THE SHOOTING EFFICIENCY OF FLEDGLING BASKET BALL PLAYERS". The findings of the paper suggests that there was significant difference in juggling training on basketball shooting efficiency. It discusses the creative use of toss juggling. Hope the said paper might be of some help.
Check out the research of Ronald Smith at the University of Washington. He is a psychologist who has done extensive work with athletes to increase coping skills and performance.
thank you for your all replies, I agree setting goals is the easiest and most successful way do build up self-confidence but in case of my female player she usually struggles with decreased self-confidence when playing against low-performance opponent and after a few unforced errors she stops to believe in her abilities being even close to lose, normally facing high-quality players she is able to hit top-level strokes and tactical solutions with an ease
Low performance players often thrive by simply keeping the ball in play, waiting for the opponent to miss. Unforced errors probably cost more points than anything else at all levels of tennis. To combat that you have to have patience. Keep the ball in play until you have an opening. Look for what the opponent does not want to do, e.g., come to net, hit backhands. Try to set up a winner rather than going directly for a winner every time.