a good way to start is by trying to recreate another existing mini - you then have something to compare your progress to. or you can work from a sketch or even just make something up as you go along.
for your armature you can use anything from copper wire, florist wire, etc. as long as its rigid enough for the job, you wont have a problem. youre just making a stick man skeleton.
depending on how you feel you can fix the wires together with solder, superglue or even putty (in this case a dab of superglue can help fuse the thing together). i then glue the wire 5mm or so depth into a cork, so when i sculpt i have something substantial to hold onto.
next you want to add a coating of putty to the wire to provide a sturdy base to your mini. once dry you can \'flesh out\' the mini, working in layers bit by by bit until youre complete!
keep your tool lubricated with a little water to prevent putty sticking. not too much mind as you want it to stick to your mini but not to your tools! like most sculpting, work with basic shapes (balls, sausages and sheets to put it simply), then smooth them out and work in the detail.
its good to work in small phases drying completely before moving on. theres nothing more frustrating than squashing something youve spent forever getting right.
there are loads of great tutorials to be found. have a look on the forums and try a google search (green putty, green stuff, miniature sculpting, etc...) but more importantly just get stuck in! its often good to find your own way of working.
as a final thought heres a list of essential stuff to have handy:
various putties (green stuff, brown stuff, procreate, etc), various gauges of wire (armature), sculpting tools (ebay), a dish for water (to keep your tools lubricated), hobby knife (for carving and removing stupid mistakes!), pin vice (for pinning additional armatures - arms, wings, tentacles, etc), plyers & wire cutters (for your armature)... blah blah blah...
:beer:
