Start with the extremities and work up to the core: The goal of Jiu jitsu is control. Humans are vertebrates – our spine is our central physical feature. Control over a human means control over the spine. The spine has two ends – the hips and the head – so those will be the two major points of control that you'll want to end with. However, you can just immediately access head and hips against a skilled opponent since they will be well defended and reaching naively for them will be strongly countered. Therefore you must work your way towards them step by step. This usually means starting at the extremities of the body – the hands and feet, and working your way methodically to elbows and knees and then to hips and head. This will be the pattern you'll follow most of the time – make a habit of it and you'll get the control you seek with much lower risk
