What have you done? You’re a disgrace to modelers everywhere.
Oh wait, guess I am too.
What program do you use? If 3ds max, send me the .max file if you don’t mind and I’ll take a quick look for you. Stuff like that only tends to happen when the skin modifier has errors in it.
On a side note, it looks like your model is missing shaders and perhaps smoothing groups too.
[editline]31st December 2013[/editline]
After taking a look at the files you sent in a PM:
This is your model with the idle animation added.
This is what the weights for the head look like. All of those breaks are different bones owning bits of the head – such as the hand. When the player’s hand moves, it’ll bring verts from the head with it, for example. I’m sure you can guess what that would look like. You should probably just truncate and remake the skin modifier to clean up all of these loose weights, or at least go through and ensure everything is weighted where it should be.
Your model has no smoothing groups. This can happen when you import an SMD file into 3ds max which certain versions of max. If you don’t know how to rebuild them, at least set everything to 1 (temporarily) to prevent it from looking less blocky.
The cause of your skin issue might be due to changes made to the model after the skin modifier was applied. It looks like you didn’t edit the modifier much if any, but verts may have gotten mixed up after something was added or removed.
Based on the last image you showed, your model is probably missing one of its masks, such as the normal map. Perhaps you listed it but never made it yet, or you just had a typo in the material.
If you’re new to rigging, feel free to import some other models and study the rigs a bit. All you really do is ensure that the model deforms properly. The person doing the rigging is the one responsible for making sure your elbow doesn’t tear or break for some reason. You can smooth joints to make sure two bones that meet control what they need to create a smooth deforming joint (studying other rigs may help with this).
Just to help in the future hopefully, helper bones aren’t necessary for making the model work, but they help produce cleaner deformation when you want to worry about that. One example of helper bone use would be the ulna and wrist in source (or forearmtwist in other rigs). If you hold out your hand and rotate it so the palm of your hand moves from facing down to facing up, you’ll notice your hand rotates 180 degrees, but your elbow rotates more like 45 degrees. A single bone cannot accommodate for this which is one of the uses helper bones aid in fixing.
If you don’t know what a bone does even after studying other rigs, you can always google it. Each animation bone usually refers to a bone or muscle. One example is the Latt bone which refers to the latissimus dorsi muscle – a muscle that runs from your back to the underside of your shoulder. Even by looking this up on wikipedia, you could probably gather that the latt helper bone is meant to help control the underarms.
I have no idea where you’re at, but hopefully at least some of this helps. Pardon my rambling though, I have a migraine and I should lay down – eventually.