This is a tutorial of a drawing completed with only a pen. I got the idea from another instructable and decided to try it out. Hope you enjoy!

Step 1: The Basics

The first thing that every drawing needs is a base. A starting point to work your way up from. In the picture you can see I have outlined all of the main parts that will be in the final drawing. here are some tips to help along the way.
1. You can never draw too lightly!Many beginners use very dark strokes that are hard to erase and can ruin your drawing. always start a little bit lighter than you think you have to. It will pay off in the long run.

2. Don't start filling in with shading until your outline is done. Especially with pen, you can't fix incorrect proportions once you've added the shading in that area, you're stuck with it. But if you wait until the entire outline is complete very lightly. you can fix any mistakes before they are engraved in stone on your page.

3. Dark to light
One technique I have started to use is to start shading in the darker values before shading the lighter ones. You don't have to do this, it is only one technique that is used in drawing and if it doesn't work for you than something else will. Anyway when you put in the darkest parts first you can adjust your other values according to them.

4. Keep at it!
When you begin drawing you may become frustrated. Don't worry about it. Take a break, cool down. It takes a lot of practice to master the art of realistic drawing. it won't happen overnight.

I hope this helps, now let's move on.

Step 2: Shading

Now that we have completed our outline and have filled in dark areas of the drawing we can start shading in! It is difficult to achieve the smooth metallic surface of iron man's helmet with a pen so if you are a beginner using pencil would be easier. As you can see the red areas are slightly darker than the gold. here is my technique for shading.

The first thing I do is lightly shade in the entire section making sure all of the strokes are going in the same general direction. Then I fill in the parts where it is darker with a little bit more pressure. A good thing about pen is that you don't have to do a lot of work to get a scratched look on the metal. It already looks that way! to smooth it out just lightly hatch in another direction as you'll see more of in the next step. always leave highlights white until you are sure they need to be darkened because with pen there is no going back. Let's move on.

Step 3: More Shading and Final Product.

Now we must finish shading and add our finishing touches. You can see especially in the section below and above the eyes the cross hatching I did to smooth it out. When you use pencil you just have to smudge it to smooth it out. After its all filled in you just go through it and darken certain areas, maybe add some cross hatching and voila! You are done.

I hope you enjoyed this instructable, it is my first. feel free to comment any questions, comments, or concerns or any ideas for future instructables. Thanks!