For a beginner just starting out in manual mode, not too bad.
Some of your animal shots are not as sharp as they can be and I know the reason. Your shutter speed seems to be too low for the subjects that you are shooting. Anytime you are shooting live animals, kids and so on, you want you shutter speed to be as high as it can be to “freeze” any action or movement unless you are going for a blur effect.
The very 1st photo of the green snake, your shutter speed is 1/15″, way too slow, even for a snake that probably doesn’t move much, but you do. Remember, the camera captures both your subject moving as well as your movements and 1/15″ is open way too long for a clear sharp shot unless you are using a tripod.
A quick rule to use is to keep your shutter speed at the same rate or higher than your focal length. It’s just a rule, not a law.
So, I see you are using a 55-200mm lens. If you are shooting at a focal length of 150mm, then your shutter speed should be no less than 1/160″, since there is no 1/15o” or higher. You’ll obviously have to adjust your other 2 settings according to your lighting conditions. This will ensure that your subject appears still, even while slightly moving.
A good example using your own photos is compare the green snake photo (the 1st on your photo-stream) to the gorilla (7th on your stream). You shot the snake at 1/15″ at 165mm and the gorilla at 1/200″ at 200mm. Notice how much sharper and clearer the image of the gorilla looks compared to the green snake. They were taken with almost the same aperture 5.3 and 5.6.
The only other thing and it takes so time to learn and get used to is using your focal points for sharper images. You have a Nikon D5200, so learn to use the 39 focus points to help better the sharpness of your subjects (like the eyes for portraits). The different focus drives are a big help as well, depending on your subject and shooting conditions.
Besides that, it looks like you are doing well, Keep Shooting and never stop learning.