This is another fantastic tutorial from Zeth Willie. I take no credit for any of this.

• Create bound shoulder, elbow and wrist joints, attached to the clavicle. Duplicate twice to make FK and IK joints chains. These should also be attach to the bound clavicle.
• FK and IK joints should orient constrain the bound joints.
• Create RP IK on the IK joint chain.
• Make FK and IK controls.
• Make 5 locators
  • arm_pv_dummy_loc : Place this where the pv ctrl is and parent constrain it to the FK shoulder joint, maintain offset on.
  • wrist_fk_dummy_loc : Parent constrain this to the wrist FK joint, maintain offset off.
  • elbow_fk_dummy_loc : Parent constrain this to the elbow FK joint, maintain offset off.
  • shoulder_fk_dummy_loc : Parent constrain this to the shoulder FK joint, maintain offset off.
  • shoulder_wrist_fk_midpoint_loc : Point constrain this to the shoulder and wrist FK joints, maintain offset off.

Something I really struggle with is OK-ing topology on a new model. So I'm going to be keeping a list of things to check. Right now it's super short because my memory is terrible. I will add to it as I discover more.

• Close edge loops around knuckles would be helpful when trying to figure out where knuckle joints are meant to go. Also they help maintain volume.

Super small little entry but wow it makes a difference ^^ I've found it particularly useful when you have to add a joint to a hierarchy that's already skinned.

• Display > Wireframe Colour
• You can select multiple joints to apply the same colour to all of them at once

After seeing the below tweet by Riham Toulan, I figured out how to use the nodes she mentioned to make a similar system in my own rigs. This may or may not be how Toulan set it up, but this is how I've done it so far.

• Make a poly cylinder for the neck. You can shape it later to better fit the shape of the neck and head of your character. You could even use a low poly version of your character's actual neck and head.
• Make a nurbs circle or curve around the top of the collar. You'll want to rebuilt the curve so that the U value goes between 0 and 1.
• Decide how many points you want to put around the collar. Put them at the base of the collar where each part of it will rotate. We'll call these bound joints for now.
• Make a number of locators equal to the number of bound joints. Attach them to the curve using the pointOnCurveInfo node, and place them above each joint by adjusting the U value.
• You may need to create a locator that sits in the middle of the ring of locators. This isn't attached to the curve, but will act as an 'up' pointer for your aim constraints in a sec.
• Aim each bound joint at the appropriate locator on the curve, and use the central locator as the up vector.
• Now make a floating joint for each locator on the curve. We'll call these control joints.
• Select the control joints, shift select the curve and bind skin.
• Now when you move one of the control joints it'll pull the curve and the collar joints will rotate accordingly.
• Make a group for each of the control joints.
• Select the neck cylinder. Deform > Muscle > Muscles / Bones > Convert Surface to Muscle/Bone.
• Select one of the groups that has a control joint in it and Deform > Muscle > Self / Multi Collision > Rig selection for KeepOut. Do this for each group.
• Select the neck cylinder and one of the newly made cMuscleKeepOut nodes. Deform > Muscle > Self / Multi Collision > Connect Muscle to KeepOut.
• You may have to change which direction the joints move away from the neck in. You can do this in the attribute editor of the cMuscleKeepOut nodes.

Voila ^^

This has been taken from a tutorial by Zeth Willie. I can't recommend his tutorials enough, seriously go check them out. He has a wonderful way of explaining things and he really goes in depth into topics.

He explains that this particular way of attaching an object to a curve is a less chunky way than the more well known 'attach to motion path'.

• Create a curve, you will probably need to rebuild curve so that the U value goes between 0 and 1. Pretty useful for later.
• Make an empty pointOnCurveInfo node using 'shadingNode -asUtility pointOnCurveInfo -n "myName". Obviously name it whatever you want.
• Open connection editor. Load the shape node of the curve into the left and the pointOnCurveInfo node into the right.
• Connect worldSpace to inputCurve.
• Then load up the pointOnCurveInfo into the left and the object you're trying to attach intot he right side.
• Connect result.position to translate.

Voila.

For some reason, Maya makes an addDoubleLinear when you attach an object to a motion path, and it connects it in a way that causes a cyclic dependency. You don't actually need this addDoubleLinear node.
To get rid of it you can shift+MMD the motion path node and the node of the object that's attached to the motion path, this will open up the Connection Editor. On the motion path node side, expand 'allCoordinates' and on the constrained node expand 'translate'. Now connect the 'xCoordinate' from the left to the 'translateX' on the right. Do the same for Y and Z. Now you can delete the addDoubleLinear node.

Make sure to remove unused influences, limit max influences and prune small influences to improve rig performance.

The profiler can locate performance bottlenecks in your scene by recording and demonstrating in a graph the amount of time that each process consumes.