It's been a long time since a posted a topic here...
Okay, so I've found some tips for easier rigging:
Add the grid
Sometimes it's hard to position stuffs when rigging using items and block right? Well now, with the new (no so new) Mine-Imator 1.0.0 Demo we could add the grid.
NOTE : I recommend 0.5 for half-pixel because it's more precise.
Create your own scale unit ! (sorta)
I've tested some scales that are might be useful for rigging, just like the 'Grid' one.
For one pixel scale :
To make the size of two pixels just do a simple math, but I'm just too lazy so I used my pal, Calculator
For one block scale :
Choose a style you prefer
Some people loves the new Mine-Imator Circles, Cylinders, Round Stuffs, and friends of them, but some doesn't. Choose your own style to create your rig, in Minecraft-y Style, pixels, boxes, and etc, or use the round stuffs.
Use Schematics
From some theories, I got this equation:
Schematics are used if necessary, when you think the shape is pixel-y round or something that are hard to make in Mine-Imator or Photoshop/Paint.NET/GIMP. Just remember dat 'equation' I made. NOTE : For now I recommend MCEdit, because you could use 3D view of your world and precise cropping.
That's all for now, If you have other stuffs to tell me I would be happy
Hope this helps!