Panel 1-Block out the general shape of the Gundam's head. The example I chose to do today is the RX-78-2 ver Ka, because it is the basic no frills Gundam. Once you can draw the RX-78, you can draw any Gundam you want. Anyhoo, Gundam staples are the helmet style head, with the IR Mohawk sensor, side vents, v fin antennae, two eyes, and face plate. As you can see, all the basics are sketched out here. Any mistakes about proportions and perspective should be fixed here! Otherwise you're ****ed later.
Panel 2-Start fleshing out those features!
Panel 3-Adding detail
Panel 4-Finished product. Quickly added some rudimentary shading and background. I'd like to note at this time that this was done in 30 min in Opencanvas with a tablet, so it's not meant to be any grand piece of art.
(This tutorial was written for in prelude for one of the Animerica Mecha contests. It's really pretty badly done in hindsight, but I figure someone might get something out of it. I'll see about making a better one some day.)