Practice moving as quickly as possible out of AC fair so that you can dash away from a shield grab and back in, or past.
Set a spacie to pressure mode and practice shield DI to make shine miss. Pracitce shield DI in general to grab from as far as you safely can, and try to do other inputs inbetween pressure as quickly as possible, and get familiar with what options work vs. what at which distances, to the point that you find yourself able to retaliate to as many things without WD OoS as possible (don't drop this option for actual matches).
Try to get a double jab as spaced out as possible while still stuffing an out of shield option, and otherwise try to do jabs as close as possible without a CPU being able to shield grab you to get more familiar with the spacing there. Find the biggest size you can do an unstale dsmash on someone's shield to break it.
Aside from learning proper tech-chasing such that spacies can't get the shine out (practice on Falco), if you want, you can try reacting off of tech-rolls with usmash chasing their movement, or shieldstopping short of where the shine would reach, angling slightly back, and grabbing out of shine's range.
Practice hitting a CPU's shield that does randomized options from distances where it's easiest to react to and punish whatever they do. Try to be able to shield nair OoS and cover roll away such that their shield doesn't come back up.