Welcome to the Team!
You should always constrain the spring when working on ball joints. If it is a strong spring (high spring rate) it may want to come pay you a visit as soon as you pop the ball joint loose.
Usually the shock will keep it contained, but if it pops out of it's seat it could damage the shock tube. I rely upon short lengths of chain; as I hate surprises.
Also never take the upper ball joint nut all the way off until you can jack the car up to put weight on the lower ball joint. Once it has popped, if it doesn't hit the nut, you can loosed the nut by hand and take it the rest of the way off to remove the upper ball joint.
Better safe than sorry!