I had a student (probably the best and most naturally skilled of all of them) who had the same problem. We overcame it by using post-it notes for left and right with big arrows drawn on, and sticking them over unused instruments eg AH and ILS (VFR obviously!). After a few trips we lost the right one, but just having the left one did the trick. As far as I know, he still uses this today (don't know what they'll say if he ever goes for an airline job)!
In my far off days of UAS flying, one student annoyed the QFI so much with this little problem that he used a big magic marker to put L and R on the backs of her white flying gloves - not good for the Top Gun image!
I think the main CRM point to remember is that it is quite common and should not be made fun of, whatever method is used.