Take a look back at a glance of Andrew Sparkes training session from the 2018 International Goalkeeper Coaches Conference. Coach Sparkes designed a training session for youth goalkeepers where he focused on crosses.
Very good point about jumping off both feet/bilateral jumping to come square to the ball (I've coached that for a long time). Beware the underhanded serve as it generates topspin - not realistic and affects the kids' spatial awareness. Good points throughout.
