[X] Plan Decapitation Strike [X] Have Sheik shoot at the eye and neck from cover behind a pillar. [X] Attack the neck joint, ducking back into cover once it's getting close to shooting at you or if it starts taking an unusual action. -[X] Try to figure out the timing for dodging its blasts, you won't always have cover. -[X] Try to discern its attack patterns in general. If the Sheikah put one in a shrine here there's probably more in other shrines.
[X] Try to go for the neck joint, ruin the mechanisms so it has to perform full-body turns - especially difficult with a body-type like that - to aim the beam at you. If it can't shoot accurately, you can test it's other weaknesses at your leisure.