There's a lot of promise here for your first time
I'll take this piece by piece to let you know what is right, technically wrong, and how you can improve. Also, bravo for attempting a fellow(even if you gave up). They are notoriously "difficult" and many dollers don't even bother.
Now, your shaping is actually good for a first try. The outer outlining is very natural, with only a few issues here and there. There are some spots in the bun where it is sharper in shape when it should be more rounded (note the right and left sides where you start to move in again--a long line before you starting moving inwards would help this). Your inner outlining(the bangs) is the major issue. There is a bump on the right side and your outline should be smooth(I've done buns several times, maybe it would help to take a look at my more recent dolls? Just a suggestion since I do them so much and looking at other dolls can be very helpful).
I'm impressed you attempted stranding, it took me ages to do it and I'm still not crazy on the concept personally. A wider palette(with 6 colors) would be helpful for you here. When stranding, you'll want to use the next light color in the palette around it, as well as lighten the strand as you go. This is a somewhat complicated concept that I know I'm not explaining well :/
Dithering gets you major points. A lot of people don't do it and it really is necessary to get smoother shading. I'm a fiend on it, so watch someone else some along and point out that I don't use it massively or that its not necessary
The outline of the bottom of your dress needs some work. It needs to be more wavy, like a real dress, right now it seems very rigid, which could work, but it needs more dropping between each level. I'll suggest waviness for now, rigid outlining is a bit more advanced and obviously I don't want to overload you. You have to basic shading concept down for the "levels", just include a bit more highlighting along the bottom portion, right now it is a bit too dark.
Also, you'll want to add folds around the waist. You know though folds in your shirt that form when you put it on? They are there for dresses too. Try adding a few lines along the waist and shading them, it will improve it a lot.
You did a great job on them, actually. I don't have much critique, your palette here was good. The highlight could be a little lighter and having a pixel go back down before the heel doesn't flow smoothly. Just have it on the same level as the second to last or one higher to keep with the smoothness.