Stinger leaders should be slightly shorter than the bait, so the hook can be positioned in the rear third of its body. The wire should lay snug against the bait, yet shouldn't restrict its swimming action.
While some anglers prefer a free-swinging trailing hook on their stinger rigs, I like to place it in the bait. First, I run the lead hook lightly through the bait's nostrils or just in front of its dorsal fin. Then I lay the stinger alongside the bait to determine where the hook will ride and thread the point just under the skin. Depending on the bait, I sometimes hide the entire shank just under the skin, leaving only its eye and point exposed.
Make sure to embed the lead and stinger hooks firmly enough to prevent them from tearing out on a cast, yet light enough so they'll pull free on the strike. If they're embedded too deeply, the hook may prove difficult to set, or may turn back into the bait.
Also, before deploying the bait, hold it firmly and tug on the leader. The strain should be absorbed by the lead hook in the bait's head. If the rear stinger is pulling forward as you tug on the main leader, the bait will not swim properly. If this occurs, create some slack in the wire by positioning the stinger hook farther forward in the bait.
Since you're working with relatively light wire, replace your stinger system after each fish. Do not try to straighten the wire, as this will only weaken it. In your spare time, make some extra rigs in different lengths and place them in plastic bags. That way, you'll always have them ready to go for a variety of live baits.
The rigs shown in the accomanying photos are effective on virtually all game fish. The necessary adjustments will be in the sizing of the wire and hooks to the species you plan on catching.