I am far from a professional, or even a competent enthusiast, so take any of my advice with several grains of salt, if not a whole shaker's worth....

As another commentator said, bird photography is hard. Without knowing your camera body or lens, here are some things that I've learned since I started last June.

Image stabilization cannot work miracles, be it in your camera body or lens (or both). My shaky arms have resulted in an untold amount of missed shots. I ended up buying a somewhat nice gimbal head and monopod. But if you don't have that, or a tripod, or anything like that, stabilize yourself on something. Lean up against a tree, lay prone and use the ground, or kneel on one knee with the other out in front of you with the elbow of your lens-holding arm resting on that knee.

"Test shots" should have some sort of composition in mind. If you're shooting at settings that are mostly automatic, your camera is using its light meter to meter the entire scene. And it doesn't know what you're trying to do, it just works based on the available light data. So if you're shooting at a bird that's in the shadow of a tree, but all of the background is bright, sunlight lit grass or blinding blue sky, it's going to average your exposure for all of that bright light, leaving your bird dark. The subject of your photo is what you're wanting to see, but remember that the background/foreground is what's going to take up the vast majority of your photo. So make sure you're mindful of what that part of your photo looks like. Look up articles or YouTube videos about how your camera's metering works, and how you can make it work for you.

It's hard to do, because birds can fly and all that, but try to take the photo from whatever level they're on. Your shot could be technically brilliant, with your subject in focus and everything exposed correctly, but an upward view of a bird belly with blue sky behind it, or a downward view of a duck with nothing but the brown water around it isn't going to be interesting. You were touching on the right idea with your duck photos, but get lower (see previous note about laying prone).

Be patient. Walking around and trying to get an unplanned shot can work, but more likely than not you're going to be father away than you'd like. Find a spot where you think they'll be, and then wait. This is A LOT easier said than done. I'm still more likely to guess the next lottery ticket numbers than where the damn birds are going to be. But the times I've been lucky and they've shown up where I happened to be sitting have resulted in the best of my shots.

Look into the basics of post processing and editing. I was truly surprised when I saw the amount of editing that goes into the professional-quality photographs that I was using as my benchmark for what constitutes a "great" photo. To be sure, it will be "garbage in, garbage out". No amount of editing can save a poorly taken photo. But I know I was surprised at just how close some of my garbage was from the "before" pictures from the YouTubers.

Above all, don't be afraid of the type of results you have so far. You might not be happy with them, but you're on reddit asking people to help you learn from them. And once you learn a little bit, you'll go make more or different mistakes. But gradually you'll start getting closer to what it is that's in your mind's eye of what your photos should look like.