Try to do a section at a time and do not shave the whole body at once. You can opt for full body laser hair removal which uses an Intense Pulsed Light laser or IPL to kill the hair follicle over the course of multiple treatments.
Let the shaving gel work on the skin before you begin shaving.
Shaving whole body. Pull loose skin with the fingers of the other hand and do not press because the lightest touch will shave just as close as.