All of the following comes from the viewpoint of an enthusiastic amateur (with very little talent)
3D design falls into 3 main areas.
Modelling/Sculpting: Creating/modifying the basic geometries and items for a scene. You will also need to learn rigging if you want your objects to have adjustable sections (arms, legs, doors etc.)
Texturing: Creating and modifying textures before applying them to the objects you made in the previous step.
Rendering: Composing a scene using objects created in the previous two steps. Applying lighting and shader effects (graphical adjustments to the textures using the rendering software).
You can also add animating into the mix as a subsection of the rendering process.
Blender is an open source modelling tool. I have it, but have not got around to using it yet. From what I’ve been told it’s not a very intuitive piece of software to learn. Many of the paid-for modelling software are supposed to be easier to learn.
Texturing is done for the most part in typical 2D graphics packages from Gimp on up. Theoretically you could even use something like MSPaint as you have little need for alpha channels. Transparencies are usually handled in the rendering software using a separate grayscale image.
If you are creating textures for a self made object then a tool such as uv mapper will be required to generate the template to guide your textures. You can also get plug-ins for some of the rendering software that allow you to place texture effects directly onto your 3D model. One example is Decalmaster for Daz Studio.
The rendering software is where it all comes together. You add your objects to the scene. Apply the textures to them. Add lighting and shader effects. Then the Render software generates your final image.
At the lower end of the market render software tends to be focused towards different styles of image. Vue 8 PLE is geared towards landscape generation. While Daz Studio 3 is more about characters.
Both of those packages are completely free. However while Vue can generate it’s own scenes straight out of the box. To get anything out of Daz you will need to either model your own objects in a third party package (such as the aforementioed Blender), or purchase/download pre-made objects. Prices for these objects range from free on upwards.
To some of us Daz is soething of a digital pusher. Your first hit is free, then you think “I could use that, it’s only $2…” “Where did that hair come from… $4” Before you know it you’re giving handjobs on the corner for StoneMasons latest release.
There is also a nice paid for piece of software from Daz called Carrara that is can do a little of everything. The full version of Carrara 6.2 was given away on issue 12 of 3dArtist.