A few things to point out - There are no holes in this head for the mouth or eyes. It depends a lot on the game, and what the goals are, but a lot of very low-poly characters for games just have the eyes textured straight on the geometry with the rest of the face. Not actual geometry eyes. Having them painted directly in the texture tends to look better with really low-poly characters anyways, plus it uses a LOT less geometry.

If this character was going to need to talk during cut-scenes, I'd set it up with a mouth that could open and some very simple geometry for the interior of the mouth, but I'm not going to bother with that here.

One other thing to point out is that I selected the collar of the jacket and pulled in some faces so that it's not just a floating flat poly edge anymore.

So on to the Hands

Most all of the hands detail is going to be in the texture. I'm going to leave the ring and pinky fingers connected to save polys, and have the hand in a loose slightly-curled position. This is using the asumption that the hand will not be animated. In this positon the character can look like it's hand is just relaxed, but it can also look like the character is holding something.

Off to the side of the character, go to the top viewport and make a box. The box should be short in depth, and nearly square from the top view.

Select the two edges of one of the sides and connect with TWO SEGMENTS. Go to vertex mode and move the newly created edges so that the first two parts ar about the same size, and the last one is larger.

Select the three faces that now exist on this side and click the Bevel button and in Bevel Type, choose By Polygon so that it's extruding three seperate segments instead of one large one.

Go into vertex edit mode and adjust the size and shapes of the digets so that they more closely resemble the appropriate lengths for fingers.

Select the edges of all the fingers and connect so that you now have a new edge in the center of each finger.

Switch to perspective view and along the top of each finger Cut it so that there are two edges along the top, and it connects to the single edge like a V like in the image below. Do this for each finger.

Do this again to create the 2nd set of joints on the fingers, then go to the perspective viewport and select all the verts in the lower half of the finger, and ONE pair of verts from the top joint, and rotate the finger downloads (you'll have to move the verts so they line up correctly after you use rotate).

Do it so it looks like the image below.

Repeat this on the 2nd knuckle, and do it for the other fingers.

Next select the edges on the side of the hand that would have the thumb and connect them and pull that edge outwards. Select the face where the thumb would exturde from and do a bevel from it. Connect the edges in it to create the joint.

Use Cut to cut in more detail along the top and bottom of the hand itself. Remember N-Gons are no-nos, so any but funky polys that we created need to be cut up into quads and tris.

Once you're satisfied with the hand, move, rotate, and scale it so that it fits with the rest of the body. Go to the Hiearchy Tab and click the Reset Transform and Scale buttons, then the Affect Pivot Only button and in the axis number entry at the bottom center of the screen, set X to 0.

Now you can apply Symmetry to the hand and it'll appear on both sides of the body.