Here's my take,
Photo 1 is OK but you should have either cropped away the branch on the lower left or included more of the tree for interest and variation. That's a compositional thing though. Technically it's fine.
Photo 2 you've already guessed it. That's a cardinal sin to have the main subject unfocused. There are a few possible reasons:
1.Were you using autofocus? With close up shots you need to take control of focus. The camera may not know what the subject is that close.
2. It could also be that you were too close for that particular lens to focus. Lenses have a minimum focus distance so backing off may have solved that.
3. Your shutter speed may have been too slow for hand holding the camera. You need to be mindful of that with low light scenes. What's weird is that it looks like you used a flash because the lower portion of the eye has a highlight. If you did use a flash then I would suspect reason number 2 because flashes are capable of freezing the subject and avoid blur. This is actually a very instructive shot because you need to think about what elements in this composition that ought to be in focus. Normally, I would want everything from the fishes dorsal fin forward to be in focus with the sharpest focus being the fishes eye. Unfocused foreground annoys me more than unfocused background so here is where I would try smaller apertures and use the depth of field preview to try to ensure foreground and fish eye focus.
Photo 3 again seems less than sharp. The water drop should sparkle and instead it seems vague. Again, you might have been too close. Another problem with this is that the main flower seems overexposed. This is an area where your imaging software can help pull back the brightness of the flower.
Photo 4 I like the composition of this shot and you were right to blur the background with a large aperture. As you can see though, the window is over exposed as a result and is more than a bit distracting. It might have been better to crop the window out. Your software can make the window less distracting by lowering the brightness. It also would have benn better to lose the Gameboy or whatever. The lesson here is that bright objects outside the main area draw the viewers eye away from the main subject and generally weakens the composition. Beginners looking through the viewfinder often get tunnel vision on the subject and fail to scan the rest of the scene.
Photo 5 is a tough shot from a lighting perspective, but again, one that can be fixed in two ways. The camera meters the scene for brightness and is overwhelmed by the brightness of the sky so it "stops down" or uses a fast shutter speed to stop too much light from entering. But the trees are not as bright as the sky so not enough of their reflected light can enter. So there is almost total loss of information in the trees as well as their shadows.
If you intend to shoot a lot of outdoor scenes like this it may be worth buying something called a graduated neutral density filter (Graduated ND). This glass filter has the top half dark and gradually fades to transparent. When mounted on the lens the dark portion blocks much of the light from the sky while the transparent area below allows all of the light transmission from the land. The cameras sensors then does not become overwhelmed by the sky's light.
Lacking this type of filter the only way to fix this is through your software, which can brighten dark pixels and darken bright pixels.
Photo 6 does a better job of even lighting but there is some distracting orange in the lower left corner. There is still something not sharp about this though. Again, manual focus and depth of field preview is called for here. Pay attention to what the camera says it is using for shutter speed and aperture in auto mode. Then, take the camera out of auto mode and into manual and play with the aperture settings and ISO to ensure at least 1/125th shutter speed and good sharpness.
Photo 7 suffers from similar compositional errors. The power lines above are completely unacceptable. You would have been better served getting on you tummy to lower the perspective to cut out the lines. I also find the people distracting so if they serve no purpose compositionally they should be eliminated.
Photo 8 is nice. It would have been nicer if you could have used a higher shutter speed to freeze the bubbles but you would have paid a high penalty and risk underexposure. Using a higher ISO would help. remember that doubling the ISO effectively gives you exactly one f-stop. Try taking this shot again multiple times, each time doubling the ISO and see what penalty you pay in terms of noise and grain.
Photo 8, well what can I say? The CLK of that vintage is one of the most beautiful cars Mercedes have ever made. I had the 320 hardtop once. This car also has the best and most effective headlamps ever invented (if it's the Xenon version.) I could always see where I was going at night down dark country lanes. In this shot though the headlamps as well as your white trainers are overexposed and so you've lost detail in these areas. We should be able to count your shoelaces. Software can fix this but fixing overexposure is more difficult than fixing underexposure.
Perhaps this is more criticism than you ever wanted to hear..
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Cheers,