Start with drawing a sausage and add a row of thin ovals along it
Next, draw a semi circle underneath the visor
Add another semi circle above the visor. Make it nice and pointy and add a line down the middle. Draw 2 little rectangular flaps either side of the head under the visor
Top off the helmet by drawing a couple of massive loopy cloud shapes to make a good plummage
Add 2 semi circles hidden slightly below the visor. Draw in 2 more circles in those and colour them in for pupils.
Between the eyes, draw a long U shaped nose
If you want your Knight to have facial hair, now's the time to add it. Draw a banana shape under his nose and a blob on his chin and colour them in.
Draw a cheeky curved line between the moustache and beard on your Knight's face
Give your Knight a thick neck-piece by drawing 2 angled lines coming from the bottom of his head and joining them together with a curve. Draw in some curvy lines to add chain mail and protect his neck for dragons and such.
Finally, your Knight needs a suit of armour! Draw 2 half circles either side of the neck for shoulder plates, then a bunch of lines in a fan shape below them. Draw a couple of lines to give an impression of arms and a breast plate and your Knight is ready for battle!