The tools/materials needed:
Soldering Iron (optional)
Helping hands or some other way to hold the work (optional)
Small length of household lighting circuit twin and earth wire
any other thin copper wire or aluminium armature wire.
What I have done is to find a simple line drawing of the human body and re-size to 120mm height for reference when making the armature. This makes things very easy when it comes to referring back to size and proportion for the armature. The only other preparation really is to strip the plastic coating off the electrical wire if your not using aluminium armature wire, turn the soldering iron on (for the copper if your soldering it) and make a coffee which is always essential for any model making as far as I am concerned.
I find it easier to start with the legs. Take a length of wire and bend it using the pliers in such a way that you get a U shaped dip in the crotch area of the armature. As mentioned I find using the printed figure that I mentioned earlier great for using as a comparator for getting the proportions correct. You will also notice from the picture that I have deliberately left the leg wires longer than the figure at this stage.
For the torso I use a single piece of wire that I wrap around the U shape in the crotch and solder in place. Again I use the printed and sized image as a reference and leave the wire extend past the head about two inches at this stage. If your using aluminium armature wire this joint can be crushed with a pliers and it should hold without the need for solder.
For the arms, its a single piece of wire again that's wrapped around the single torso wire at the appropriate height (using the figure print as reference) and soldered into place. I then use the pliers to bend both sides of the wire into the shape of the shoulders and arms and trim off the excess length with the wire cutters at the finger tips of the armature. (again aluminium armature wire can have a crushed joint over solder.)
Finishing the armature
For the feet I use the thinner gauge wire and take the reference point for the feet from my printed drawing. I solder a wrapped piece of the wire to the frame and then trim/bend as required. the thinner gauge wire is better for the shoes, especially if the figure is to place in an action pose and the feet flexed. I would add that as I get more and more confident with sculpting, I tend to leave the feet armature out completely, opting to sculpt the feet in a separate sculpt and then glue to the body once both are baked. Either method is OK to do and I know that there are quite a few more styles adopted by other model makers for you to choose from.