Practice, practice, practice. This is something I set myself to do and it is progressing although not as easily as anticipated.

Like you, I decided to simply not take the poor shots after having developed an eye for what is a good photo in my vision. I started with a ratio around 100:1 from before knowing what a good photo is! With a better idea of exposure and composition, it did not take long to get to 10:1 but from there it has been very difficult, taking years to get to 8:1 and now around 6:1. Note that this is an average ratio and some situations are just harder. The more motion there is in the scene, the higher the miss-to-success ratio.

Things that made the biggest difference:

1. Pre-visualizing. Looking at elements around you and deciding if there is enough to make a scene.
2. Inspecting the whole frame. Most people shoot when they see something they like in the frame. It is much better to shoot when you only see something you like in the frame.
3. Double-checked edges. Using a camera with a 100% coverage viewfinder is immensely relieving for this. I make sure nothing or no one is crossing the edge of my frames, unless shooting pattern of objects or crowds.
4. Press the shutter slowly. While releasing the shutter carefully watch if anything is come towards the edge of your frame and if your camera is level and make sure it stays that way.
5. Learn to see the light in a scene. Particularly contrast, since cameras have a limited dynamic range. You will have a better idea of when a shot cannot be exposed properly. Now I usually pay particular attention to the time of day and which way a subject is facing to guess when the light will hit it in a better way since light changes along the day.
6. Review your shoots as soon as possible. Learn from them and repeat. This is essential when passing the 10:1 level. A lot of shots seemed thought out at that point but when seeing them in context, I started seeing why some were better.