There seem to be as many ways of making an armature as there are sculptors, and I have tried several different ways without really forming a view on a favourite, other than it being dictated by the eventual form of the sculpt. Here I discuss the approaches I've tried.
Jeweller's Aluminium Wire
One of the first places I looked for help on how to start sculpting, was
StormTheCastle on YouTube. Will has a particular approach to forming armatures, and I went to Hobbycraft to grab a load of different types of wire. I started with yellow anodised aluminium wire for making jewellery, which was easy to handle and shape but actually nowhere near robust enough to stand up to a lot of the pushing and pulling that goes with sculpting (well, in my hands anyway).
I tried 0.6mm diameter wire, which worked reasonably well (see The Woodsman) but is really far too flexible. 0.4mm aluminium wire I find occasionally useful, as when braided this is quite robust but still fine enough to use inside arms, for example. Here's an aluminium armature:
Copper wire is a bit more robust, whilst remaining easy to shape, and I still use it occasionally. Even 0.8mm diameter wire is a little soft, particularly for fiddly bits of sculpting. Here's another armature, made the same way as I normally do, this time with the anatomical landmarks indicated in black.
My current normal armature material is steel gardening wire, with the green plastic sheathing stripped off. Although this needs rougher handling to get into shape, it is robust and doesn't move when I work on it, which is particularly helpful when trying to get the armature's pose correct. Aragorn Marks recommends steel wire in his Miniature Mentor tutorial, which is why I tried it. This worked especially well for my elephant men, as the trunk did not move at all, despite how much I was working the putty.
Whole Body and Part Body Armatures
I mostly create one part armatures, with all four (six) limbs, as I find this easiest to visualise when checking proportions, posing the armature, and coming to lay down the muscle layer of putty.
Some sculptors like to build the armature up by gluing/soldering/epoxy-ing spine and arms (e.g. Heresy, Ebob) whilst others prefer to have an arm-less armature (e.g. Aragorn Marks, Ramon Laan). The advantage that part body armatures like this have is the ease with which the torso can be finished.
I've tried both ways, but prefer the easier way by building a whole body armature.
More to come in due course...