Aim small miss small.

I am a big fan of dividing beaches up into small areas and covering those smaller sections really well.
If you try to cover too much of a beach, you run the risk of walking over valuable targets. 
The majority of beach and water hunters I see are straight line searchers, people who walk and search in one straight line at the beach. 
The two most common type of straight line hunters at many beaches hit the low tide. Searching a straight line way out in the water, or along the beach next to the waters edge. 
When you search in one straight line at the beach, you are not doing yourself any favors except for extra cardio from all the walking. 
You could probably get lucky by walking a straight line along the beach, but hoping to stumble across something good is not a good beach or water hunting plan. 
In my opinion, you are better off doing the least amount of searching in a straight line as possible. 
I prefer to use a tight zig zag search pattern across a beach, hoping to latch onto a target or two. 
When targets are detected I narrow my search pattern, instead of completely walking away from the area in a straight line as many other beach and water hunters do.
I have found far too many pieces of valuable jewelry to ever walk away from an area with multiple targets. 
Sometimes, I have recovered great finds only after completing a different search grid over an area.
Ferrous and non ferrous targets hide jewelry and coins, a nice tight search pattern gives you a chance of recovering the maximum amount of targets in an area.
Some people like to cover all the beach in one hunt, I prefer to cover one area of the beach in one hunt. 
This superb Tiffany & co platinum ring with a 1.5 carat diamond appraised at $10.000.00, the diamond ring was my reward last year for sticking around at one spot. 

I began recovering coins and instead of walking down the beach to a busier section, I hammered the small area with a pulse induction metal detector.
By aiming to cover a small area really well, I know if anything of value is in that area, it is more than likely coming home with me. 
The diamond ring was recovered after using a tight spiral search pattern away from the highest concentration of clad coins and assorted junk targets.