First thing I suggest you do is invest in a good knife. Not a typical long slender fillet knife but a good hefty butcher knife. I use a 10 inch, hollow edge, butcher knife. The blade is an 1 1/2 inches wide and has much more of a blunt point than a fillet knife. When I fillet a large chinook I wish I had a 12 inch blade.
I generally start with a fish that has been gutted. First, holding the fish just in front of the tail, roll it up on it belly and with a swift stroke remove the dorsal and adpose fins. Then with the fish laying on its side, put the point of the knife inside the body cavity, just behind the head and break through the ribs on top and bottom of the back bone. Now push the blade through the fish using the upper of the two small cuts you have made through the ribs. The blade will now be sticking out the top of the fish with the sharp edge toward the tail. Now, taking the ribs and all, cut toward the tail stopping about 4 inches from the tail. It's important not to cut the tail end of the fillet loose on the first stroke. That's because when you roll the fish over and cut the second fillet the first fillet will hold the backbone straight while you are working. Now roll the fish over and run the blade out the top of the fish like before. Again taking the ribs and all, cut all the way to the tail. This time cut the fillet loose from the tail. Cut both fillets loose from the head and cut the first fillet loose from the tail. Now remove the ventral fins.
It's important to take the ribs with the fillet because the ribs and the membrane between the ribs protect the meat if you freeze it and, hold the juices in when you cook it. It's also much easier than trying to cut the fillet off the ribs. I gave up doing that a long time ago. The ribs are easily lifted off the fillet after you cook it.
This method is both quick and simple for steelhead and salmon of all sizes.
Just like keeping the skin on the fillet, the ribs protect the meat during freezing and cooking.
It all depends on the knife. I bought mine from Englund Marine during one of the fishing shows here in Portland.