Are you talking about sculpting in plasticine, which maybe could be moulded and cast to make puppets? That's good, because you can cut clay away and stick more on until it looks like you want it too. (I'm doing some carving of Hebel aerated concrete blocks at the moment, and it's really hard, because with carving you can only cut away. If you take too much off you are screwed! )
I start with an idea of what I want to make - maybe it's a dinosaur, maybe a portrait of some well known person. So first I get photos from different angles, so I have something to base it on.
(Actually, that is a good way to improve your skills, trying to get a resemblance, you have to keep at it until you get the likeness. With some of mine, I posted pics here without saying who I was trying to do, to see if others could pick it. After a while it's hard to tell with your own work, you need fresh eyes. Even not looking at it for a couple of days can help.)
Then i get some modelling clay and work it in my hands to warm it up a bit, and make the basic shape with my hands.
I use various tools to get the finer detail - some are bought, some I make from a nail glued into a stick of wood, or by grinding a broken hacksaw blade. I make a flat rounded tip from the broken end, tapered on one side so it has a sharp edge, and it can cut, scrape, or smooth the clay. With plasticine you can scrape away to smooth the surface with a ribbon tool. That's a loop of flat metal on the end of a wooden handle that you drag.
Here's a video the process where I wanted to make a head of writer H P Lovecraft. https://www.youtube.com/watch?v=5fWdZnQRzB0 To be honest, it took more trial and error the you see here to get the likeness. I had already sculpted the head when I decided to make a tutorial so I started again for the camera, and it went much easier the second time. I knew where i was going, the first time I had to keep stopping to puzzle it out. I swapped to my original sculpt just before making the mould.
If it is something original you are making, you may still want to see references of different creatures to incorporate some of their features, so you might still want to get some photos together. Or you may start with a couple of sketches. I often jump straight in with the modelling clay if I am making some random human characters that don't have to look like anyone in particular.
If you are using a polymer clay like Fimo or Super Sculpey, they behave a bit differently. It's not as easy to shave off the surface, the whole lot tends to drag along with the tool. I'm not good with it, I prefer plasticine or water based clay. So it would be better to see something from one of the art doll makers who uses it, to see how they work with it. Like this one: https://www.youtube.com/watch?v=DLPCuHBbI64
Really, I learned because I had to make stuff as a props maker, so I just did it a lot, and in time it got easier. (Easier to reach a certain standard, but then I see something that is far better than I can do, so I have to try to move up to the next level.) Part of it is really looking at the reference photos, and you find there is nothing like trying to make a drawing or sculpture of something to make you really notice the proportions and details.
If yo are sculpting a whole figure, you need some kind of armature to build the shape onto - whether it is in a neutral pose, like a typical stop motion puppet, or a static sculpture with a more dynamic pose. Aluminium armature wire is good for this, but I have used steel coat hanger wire when I didn't have anything else. As long as it holds the shape and supports the clay. Usually I have a wooden base to stick the wire into. You can sculpt over the armature you would use in the puppet, but more often I mock up something simpler that I can bend in different places, so If i don't like how it is looking when I put the clay on I can make some changes. (Often I want to cut more clay away, but then I hit the armature inside and can't take any more away, so I want it as slim and simple as possible to give me more choices.) Then I make the final armature later, to fit the plaster mould.
There are a lot more videos around, mostly in time lapse which makes it all look easier than it is, or at least quicker. You'll see some in the Similar Videos on the right. But watching doesn't really teach you as much as doing it with your own hands.
Good luck with it!
These videos are quite useful for Sculpey.
Thanks for the advice! I use plasticine and have been working on a minotaur for a week or so, and I was having difficulty sculpting out the head of the puppet. I'm so bad at sculpting. I'll probably just end up sucking it up and spending 7 hours getting it just right.
There is some confusion over the term 'plasticine'. In the UK we use it to refer to the stuff Morph and Wallace and Gromit were made from. I think that others may use it to refer to wax-based modelling clay such as Chavant Plastilina. This comes in three hardnesses. Personally I use hard mostly for sculpting, but it is not that easy to use unless warmed a bit first. The best thing is that it is hard to accidentally squash some detail you have just done. You can smooth it using lighter fluid or (safer) d-limonene, and it can be melted. If you can master the use of it, then it is possible to do very finely detailed sculpts.
One great advantage is that Chavant does not contain sulphur, which can inhibit silicone, so if you are sculpting to make a final piece in silicone via a plaster mould, this is the way to go.
7 hours of videos? I spend maybe that long or even a lot longer on a sculpt!
Usually I only sculpt the bust of my creatures (I use the build-up method). I have been trying to get my hands on some proper sculpting clay. Right now I have some cheap clay I bought from the store. What are your thoughts on the Chavant clay?
Chavant clay is brilliant. I use hard and soft, also Beau Touche, which is equivalent to soft. It is very economical as you can use it again and again. You need a hairdryer or some source of heat to soften the hard. Takes a bit of getting used to, so watch some videos. Stuart Bray is superb.