I've done what I can for this thread in trying to break down how I do it. That doesn't not mean how it should be or you should it's just suggestion so feel free to vary from this.

1) I start out by trying to block in shapes on a bit of perspective. I need to know where the hell shapes are going or we're lost.

2) I block in what I know of the body (from practicing and being a lazy f) blocking in shapes from the shapes i've laid down. This is on another layer.

3) Continue blocking in shapes making sure i'm getting at least a vague suggestion of what this is supposed to be.

4) Try to clean things up a bit add clothing etc

5) Continue adding detail until you lose you f'ing mind or you decide to rush to finish it up. That comes down to patience.

Hope this helps. Best of luck! My best advice is to learn shapes and perspective as it will help you tremendously as it has me.