I’ll call this fundamentals as opposed to an aiming “system”, as it is more about what to do after finding the aim line.
First, find the aiming line however you are comfortable with, such as ghost-ball. Lay the tip of your cue on the table directly behind center cue ball on this line. Keep your back hand under the cue, fingers near or on the table. Standing behind the cue, bend down and eye-ball the line, be certain your cue is perfectly on it. Now without moving the cue side-to-side, slide into the shot placing the bridge hand under the cue. (That takes practice.) You are now in shot alignment. If you stroke straight, you should hit the ghost-ball dead. This is the time to apply back-hand english to the shot, if spin is required.
There are other fundamentals assumed here, such as arm, foot and body placement. The emphasis is getting the cue stick on the shot line first, then stepping into it. I apply this technique often times when I’m on a tough shot, or if I’m having an off-day and just need focus.