Rotate when needed to keep your wheel wear even. Bearings and Spacers Keep bearings clean and dry. When you rotate the wheels, wipe off the outside of the bearings with a soft cloth. Do not lubricate the outside of the bearing. That will attract more dirt.
Some bearings are serviceable.
The shields, crowns and balls can be removed and cleaned. Every time you skate, check the brake pad for wear and proper attachment. That line is clearly marked on the brake. Keep your brakes in adjustment so that they can be engaged but do not interfere with your normal skating. Choose an ABEC rating appropriate to your skating style.