I was lucky enough to get a lesson a few years ago from a commercial fisherman with several decades of experience on bleeding fish.
I carry a low hieght flat plastic tub on the boat and bleed my fish in it rather than dangerously hanging over the side of the boat in a swell or making a mess out of my boat. The low edge of the tub 6" makes cleaning easier as you are not reaching down into a deep tub.
Bonk the fish first, nothing to do with being kind to the fish, if the fish jumps while you are bleeding it you are likely to loose fingers.
With the fish laying flat, it's head pointing to your left and the sbelly away from you lift the gill plate with your left thumb lifting the head of the fish slightly off the ground. Insert the tip of the knife into the opening inside all of the gills and with the point facing slightly forward cut through the leading edge of both sets of gills cutting in the direction of the belly-side of the fish. After you clear the leading edge of the cartiledge turn the knife towards the tails of the fish and cut in a half moon direction around both gill sets. At this point you are in the soft dark material behind all the gills so there is virtually no resistence. When you get to the end of the gills with the knife facing towards the mouth again reverse the direction of the blade back towards the belly-side and cut through the cartiledge on the other end of the gills. Using this system you remove both sets of gills at the same time, never hae your fingers in the gills near the knife and with pratice it takes about three seconds.
I then slit the belly, check the stomache contents to see what they are feeding on, scrape the blood line from the backbone, rinse and move the fish to my primary cooler and dump the contents of my cleaning tub overboard.
Give it a shot, with practice it's a safe quick technique!!!