Before any submission, learn the map. Positions have a pecking order, and understanding it is the fastest way to stop drowning on the mat.
Jiu-jitsu is a game of positions before it is a game of submissions. Every roll is a fight to climb a ladder of control, and the tap is usually just what happens at the top.
From most to least dominant on top: back control, mount, side control, then knee-on-belly and north-south as mobile options. On the bottom, guard is the great equalizer — the only bottom position from which you can attack and reset.
Position before submission. Escape to a better position before you try to finish from a worse one.
The practical takeaway for beginners: spend your first year learning to hold the good spots and escape the bad ones. The submissions will come far more easily once the map is second nature.