picture quality is good, but all the shots are a little dark, which is nothing wrong in itself, but you want your subject to still be properly lit. Ironically, if you want to do really dark pictures, you need to work with light in order to create this darkness.
some of your pictures should have been, in my opinion, cropped, in pictures #1, #3, #4 and #5, the subject is centered without a real purpose (it can be arguable in the tree picture tho, less so in the others), cropping would have solved the problem and given a much more dynamic image.
I personally stick with the rule of thirds unless I have a really, really good reason to center my subject (like working with symmetry for example, with non centered elements working towards leading the eye in the center, where the subject is).
If you really want to work with darkness, you should try those Led lights you can find for cheap on amazon, get a couple and a good stock of R6 batteries, I feel the flash is too limited (for me, at least) to work with small objects such as yoyos, I prefer working with directional lights aimed directly to my subject, therefore preventing the darker areas to be lit. Lighting the ceiling with a flash will not do that.
I was with my friend (nowa on the forum) and we took some shots to try out my new camera and some old lenses.
dark shots. we used either 2 or 3 lights. 1 on the side of the subject’s face, 1 aiming on the yoyo, from the other side, and on some, one more lighting the face from the front-ish. Medium to low ISO (200/800), medium aperture (f5.6 - f8, sometimes a little more, maybe 2.8ish), rather fast-ish shutter speeds (1/200-1/500). mostly 50mm lens.