I did this piece about 10 times for a total of more than 2 days. I learned a lot and found out different technique that the teacher don't use cause I have my own style to create meshes that also works for me.
Don't worry about the hole near the thumb. We don't see the inside of it so it's not perfect and it's ok.
Hi 
maxcady ,
Some things that I noticed immediately:
These Faces for instance:
Let's isolate them to get a better view:
Pay special attention to the selected N-gon and it's 'center' (the white dot); the Catmull-Clark algorithm (Subsurf Modifier) depends heavily on that center point.
If we now enable the Subsurf (one level only here), we get this mess:
In general, when using Subsurf, corners, especially concave corners need holding Edges. This crazy geometry is also visible in Object Mode:
Furthermore, I am not happy with this kind of non-manifold geometry (even apart from the extrusion having no thickness):
I might find more when I look longer, but these rpoblems need 'immediate' fixing 😊
Really like the fingers (and thumb) though 👍🏻
how do you isolate the selected vertices and how can you see the center white point?
I really wonder how I left the faces with no thickness....
Ok. I just restart all over with my new skills. It may be not perfect but I think it's better. please tell me if there is a slight mistake, as I do not get tired. here
Shift H. Cool. I gave another try, I deleted the hand and I did model the hand once more. Did you look at the result? It's in my upper comment.
those 'centers' are an Overlay and can be enabled here:
They are the calculated average of the Vertices that make the Face and therefore can even lie outside of the Face as you can see.
With Catmull-Clark, (in simple cases like this) each Edge of a Face is subdivided once to make new Vertices and each original Vertex shifts halfway towards that 'center point'. The complete algorithm is slightly more complicated, but this might already help understanding some of the behavior of the Subsurf Modifier.
As for the model; much better!
There is one area, where you have a lot of Double Vertices:
and, although some of them are intentional and okay, there are a few that cause weird shading and geometry:
and I'm not sure what I am looking at.
If this is meant to be like this, you can leave it as is of course.
The rest of the hand looks great to me; another job well done Max!
I think I know why. It's because separated the hand in 2 parts to create some effect then I merged them together. The effect that I wanted to create has disapeared. And I didnt notice it! The question is why the effect has disapeared???
This is the hand without the effect: Here
I succeeded to make that effect: effect
I soon as I merge them with CTRL J, it creates problems
This is the unmurged version: unmerged
Well, LOL! It is because I deleted the hand and I remade it all over again. Sometimes, there is a mistake we did and we don't know how it happened. Then we start all over, and everything's working fine.
I will enable the white dot center all the time to understand the mechanic of Blender topology. :-)
