Sculpt modeling works similar to the way we may sculpt in real life. This is a fairly new way of modeling in 3D. If you have experience sculpting stuff in real life like clay models, then you’re going to have a lot of fun digital sculpting. There are many 3D applications dedicated completely to sculpting, such as ZBrush and Sculptris. Blender can also function as a sculpting tool. These applications contain a bunch of different brushes which may aid in sculpting your model the way you want it. There are brushes that can add form to your model and make it bumpy and rough. There are brushes where you can smooth things out, or use an image texture to add indents (like pores) into a model. You can also use image textures to create lizard skin.
You can literally turn a cube into a giant hulk beast using nothing but sculpting. This is possible by something called dynamic topology. That is, as you use your brush to paint and control the look of your model, the sculpting software is smart enough to dynamically add (or remove) vertices and reshape your models accordingly. You don’t have to worry about pushing and pulling vertices, or extruding and adding loop cuts and so on. Unleash the artist within you as it is the artist that is in control, not the software. And that’s a good thing! We don’t want software to control or restrict how our models will look. Only our imagination should have the permission to do that. And sculpting is a step forward in the right direction.
One drawback with sculpt modeling, however, is topology. If you want to stuff up your topology and create a mess with a bunch of vertices and faces that are hard to edit, then sculpting will always give that. Almost always, dynamic sculpting will give you more vertices than is necessary and may find that it hogs up a lot of your PC’s memory when your sculpted models start to get detailed. Many sculpting software applications do have features that smartly control memory consumption but still it isn’t overly smart. If topology is important (that is, if animating, or memory consumption, or even selling/working for someone), then sculpting is best used in combination with retopology (explained in this post).
An artist would generally approach sculpting by starting with a cube or sphere. It doesn’t really matter in this case. This is the base model. From there, the sculptor would build up form using the brushes and constantly refine/smooth. There are no specific rules to how to sculpt. Both Sculptris and Blender are FREE! Go and download it and then create whatever you like right away! Just do what your inner artist tells you.