The best way to move your doll is to have her on a rolling chair such as a wheelchair or office chair. This makes it easier for you to avoid injury and it is less likely the doll will be dropped.
When this is not an option, either lift the doll in the bridal lift (one arm behind the shoulders, the other beneath the knees) and lift with your legs rather than your back, or lift the doll from under its arms to carry it. Make sure to check some basic squats-training for basic back/leg protection & strengthening.
Make sure to keep the hands in a protected position crossed over the doll’s chest, or over your shoulders to avoid damage when the doll is set down.
For sex, you can use sex swings, light bondage kits, and pillows to lift and pose your doll for play. When bending a joint, use a firm two-handed grip with one hand on either side of the joint. Firmly and slowly move the joint to the desired position being careful not to twist the skin unnaturally. Never try to pull your doll towards you by the doll’s hands as this can severely damage the wrists.