My favorite answer.....depends.
Different people use different techniques. Techniques vary depending on subject, type of lens (wide vs. macro), strobes, strobe arms and whether you use one or two strobes.
I'm sure you will get many replies with varying suggestions.
First, I prefer KISS (keep it simple stupid). This way I can concentrate on composition rather than technical aspects such as camera and strobe settings. I add complexity as I need, but try to keep things as simple as possible.
Generally speaking, the strobe needs to be away from the camera and above the subject to avoid backscatter and produce a more "natural" effect. (The sun is generally above and to the side of us).
Some prefer to hand hold their strobe. I find this difficult and error prone. Marty Snyderman taught and shot this way, but has since recommended abandoning this method. Often the aim of the hand held strobe went wacky as soon as the shooter looked through his viewfinder again. I find that fixing my strobes for the type of shooting I will be doing on the dive to be sufficient for most shots. No adjusting. No movement.
Macro shooting. I shoot macro in TTL mode. I try to position my strobes above and to the side but much closer to the lens than normal. I use my aiming lights on my strobes to align the beam just behind the position of the my likely subject. I do this at the beginning of the dive while pointing at some object in the sand approximately 6 inches further away than most of my macro shots. I then turn off my aiming light for the rest of the dive (during daylight dives).
Wide angle. There are alternate techniques to wide angle. My starting point is to get both strobes away from the camera as far as possible. I may not position my strobes quite as high as normal depending on what type of shot. I position the strobes further back trying to stay close to the film plane, whereas with macro, I have the strobes forward towards the end of the lens. I angle my strobe beam only slightly inward toward the lens. This allows use of what is called edge lighting where the center of the shot is getting an overlapping edge of each of the beams. If you are only using one strobe, you will want to keep it closer in to your camera.
In dive adjustments: I have articulating arms that can be easily adjusted. This is a two-edged sword. You can overdo the adjustment. If I am trying to get something under a ledge I will drop the strobes lower. If I am doing CFWA (close focus wide angle) I may change my strobe angle and power settings (I use manual strobe power settings on wide angle for the strobe pointing to a close up subject that is on one side of the frame.
When using one strobe for macro, I may adjust the strobe position depending on where I want the shadow of the subject to end up.
By the way, your strobe shouldn't be moving around during the dive unless you want it to.
I don't propose that these techniques are the absolute best answers. Others may provide better advice. I can get very experimental with my strobe aiming, usually with lousy results. I await the comments of others.
