Sniping and Metal Detecting.
Sniping is great for searching clean underwater crevices and pockets.  There really is no technique other than maybe just having a good underwater flashlight.  You simply hold the snipe tube (pictured) by the handle and push the end underwater on top of the area that you want to search.  Shine the light in the spot that you are looking and Viola, instant determination of any values (nuggets) in the spot.  Then you would use some typeof suction tool, even a turkey basting bulb to sniff out the gold. Sniping can also be done without the Snipe tube.  I is just the simple matter of searching the streams for cracks or pockets that would contain gold. You can do it just by walking and looking or using a diving mask and snorkel.
Metal Detecting can be done with many new types of detectors out there. I will leave it to the experts and your own opinions on which to buy. To ask all you need to know about detecting just click the link and ask away in the "Metal Detecting " forum...but if you do decide to purchase one, Please support the place where you asked the questions.
Ask them here!
Whatever you are detecting for, select the right detector and the key is always, location, location, location. If you are after nuggets, the try some old tailings piles and dirt road beds around old mining areas. You can find some places by clicking here.   Coin shooting and relic hunting are great for all kinds of areas such as old school and church yards,  beaches for jewelry and coins,  and about any other imaginable metal object out there.