TedShatner
Here is something I wiped up quickly in Photoshop to help you out with process and proportion. Now, I admit it's a not a very good pic, normally I'd do this on paper and then ink it and then scan it into the computer but this is quick and dirty to illustrate the point.
Notice how I start with a stick figure sketch to establish the proportion. The figure stands about 7 1/2 heads high. His crotch is the middle of his body from top of his head to bottom of his feet. His fingertips of his hand ought to fall about to half way down the length of his thigh.
After the basic pose and proportions are mapped out with the stick figure, I can rough in the meat of the character. This also need not be very elaborate. It's only to help you quickly establish the position of the figure. Once the body is mapped out, the costume can be sketched in, in this case a TOS security guard. Even if it was a guy wearing a long flowing cloak or a girl in a floor-length formal gown, you still always need to follow these steps to rough out and establish quickly the form of the person under the clothes if you want to maintain realistic proportion.
Once the rough sketch work is done in the three step layers I described here, then you can draw the heavy final lines, with a framework of lightly drawn sketchy lines to guide your hand. The final drawing will be well proportioned and at least not kinda freaky looking.
Well I hope this is helpful. This is a common way to draw and I know of plenty of pros who follow more or less this exact routine. In fact, very few do not. Please do at least one drawing like this and let us know if you like this system.
Cheers
--Alex
(PS it still allows for error so you do still have to get it right in the stick figure phase. Now that I look over this again, I think I drew his forearms a little too long, something I keep having a problem with. Oh well, we all have lots to learn. Keep drawing! Have fun with it!)