Piggybacking on other advice...
Checklists for routines are great - either taped to the desk (covered in packing tape) or laminated on a ring clip). However, most tasks vary day to day. I often put a list of numbered steps on the board as I give the instructions. When I see a kid off-task, I can get their attention (even if they're across the room) and hold up fingers to match the numbered task they need to do. It's simple, less disruptive, more private, and works for almost all kids... as many need help from time to time at this age.
Of course this is what works in my classroom. Your child's teacher might find a different system works better for him/her. Just thought I'd share something that has been effective for me. Good luck!
