If you think you already know what a rig is, then you probably need to read the definition of "rig" and "rigging" before we get started. It's important to note that an armature is not a rig, but a rig can be an armature. Assigning a mesh to be deformed by an armature is not rigging.
A rig should always be designed for the types of animations your character is going to be performing. Only make your rig as complex as it needs to be to allow for the types of actions you need.
To make everything with the armature easy to deal with, we're going to make our character in the crucifix pose. If he's not, you will have headaches trying to deal with bone roll angles. Once Blender can easily allow the user to roll the bone to align with a roll target, then I'll edit this tutorial for that. But in the meantime, we will use vertical legs and horizontal arms. We will build the legs from the side view and arms from the top view.
Center the cursor (shift+c) and add an armature. In Object Mode, press alt+r to clear the rotation. You have to have a bone for the hip, and it needs to stick out of his front or his back, so take your pick, because they both look bad. Don't point the bone upward at some odd angle, we need to be able to roll the hips easily, and to that end, we will place the bone horizontally.
In front view, place the cursor and add a bone. IMAGE
In side view, move points and extrude them until your chain looks like this. Note the slight bend in the knee. This is very important! IMAGE
Snap your cursor to the root of this chain (shift+s) and add a bone. Now select the points at the hip joint and the ankle joint, and snap the cursor to the selection. IMAGE
Select the tip of the newest bone and snap it to the cursor. IMAGE
Now give these bones some names. It's a good idea to use the same names I do to avoid confusion, since I will refer to the bones by name. Select upperleg.l and then shift+select leg.l, and press ctrl+p to make upperleg.l the child of leg.l. Do this again, but make leg.l the child of hip. IMAGE
In front view, center your cursor and select