Sculpting can be the answer, as you are not limited on poses for parts, and have limited customisation. But for those starting out, a little practice is needed, and some lessons learned. Here are some tips which should help you improve sculpting skills:
In the early stages of my sculpting, I found out that it's very hard to sculpt with no support of a frame of some description. More often than not, any pressure applied by sculpting tools would move the parts undesirably, meaning constant alteration was needed. Also, once dry, the putty parts were too flimsy to last. Armatures are the solution (well, for bigger parts). An armature is essentially a skeleton, adding strength, structure and shape to anything you make.
A good source of armatures is paper clips. Cheap (around £1 for 200 clips) and easily available, they can form a strong supporting frame, with careful bending and super glue. As a tip for making humanoid models, make notes of real body proportions, so as to avoid misshapen bodies (unless that's the aim).
Two: Sausage Man
Three: Different materials
Plasticard can also be used in the sculpting process. For example, I have seen a number of people use plastic tubes to form the basis of Obliterators, and I have used it to form this Reaver's head. Generally, leave plasticard for larger sculpts, and make sure you reinforce the structure. A lot of pressure will be put on it when you're pressing down on and forming the layers.
Four: Tools and lubricant
Don't be confused by the latter, this will come soon. Tools first. A good set of tools will allow you to sculpt a wide variety of textures: large flat tools will help with large smooth surfaces, and thinner, pointy utensils will allow precise sculpting, such as doing hair and chain-mail suits. You would find it difficult to find a master of all tool, so shop around for a number of different items to sculpt with. Things such as cocktail sticks and small spatulas can act as primitive tools, whilst many companies will sell you sets of multi-pointed sculpting tools, which are more than worth the cost.
Now, lubricant? Don't worry, its not as perverse as it sounds. What you need is something to keep the outer layer smooth and hole free. There is nothing more irritating than having a sculpt solidify with lumpy surfaces and pits. What I use to ensure a smooth surface is a tub of Vaseline. Apply a small dab on tools, and surfaces will appear smoother and flatter as you sculpt. It's also useful for cracked lips, apparently....
For trimming and reshaping sculpts, I recommend Sandpapers of varying types, to help shape the material for subsequent layers, or to get angled,even shapes.
Als a final important notice, the voting for the new name closes on the 30th June, so get voting: http://rock-geek-journo.blogspot.com/