Well, Aunt Ruth said to use special pencils to add detail, and while I think that's important, what's more important are the proportions (anatomy), gesture, and idea behind it.
I have the same problem sometimes.
I would recommend making more loose sketches as opposed to finished work. Get the idea down and elaborate on it if necessary. It looks odd if you concentrate on little details without understanding the things you learn while sketching.
It doesn't matter how "fancy" your supplies are at this point. I sketch with normal pencils all the time.
I really don't consider a mechanical pencil fancy equipment. I mostly use them for school. Regardless, this is video illustrates the technique I was trying to describe.
Oh, I wasn't referring to you when I said that... Sorry if it was offensive.