Draw the basic shapes required.
The helmet looks big.
The right arm is straight back so it is only drawn as shoulder and hand.
Draw in the left arm and the shoulder guard. The sword and the wrist. The helmet has eye holes about half way across it. There is also a decoration above the eyes.
-Make sure his right arm comes from behind the shoulder guard and you can see how his wrist turns to hold the sword out away from him.
Add in the main detail now.
Make the sword and shield look more 3D. And detail to the decoration on the helmet to make it look like it is also more 3D.
The lines on his chest are diagonal to show the way his body is angled and his movement.
Add a belt and a line for the chain mail at the bottom of his armour.
-The line isn't straight to show that it is chain.
This is the finer detail step, where it starts to really look like a knight.
The chain mail has been done with 3/4 circles, so that they look like they are linked. You can see the chain mail in the gaps between his shoulder guards, arm guards and chest armour.
The eyes are done quite narrow so that he looks more serious and dangerous.
This step is to show where the shadow and highlight would be. This makes the drawing look more realistic.
The light will be coming from behind him in this so his front will be darker than the edges.
The metal of his shoulder guards and helmet will have more highlight then the rest to show that they are more shiny.
This is the final image and you can see where the armour will be reflective or shadowed. You should be able to use these techniques any time you are drawing armour.