I would suggest not using this picture COMPLETELY, but I found a very basic sketch of what a knight is, so this might give you some feedback on how a knight would look like. In my opinion, drawing knights in full plate is easier than people, just for the fact that you don't have to draw lips, noses, and ears (a common problem for apprentice artists), and you could draw the shoulders as big as proportion allows and it will not get ridiculed a bit =) Hope this helps you!
If possible, I could give out some layers information so you could get effective shading done. Of course the shading done on this knight sketch is inaccurate, so..
1st layer: skin (if wearing a 4th layer of plate helmet, give a generous amount of shading, almost dark-gray to black.
2nd layer: leather/clothing [optional] (if not wearing 4th layer plate boots, wear this. Those that aren't wearing 3rd layer or 4th layer, give little shading at all, since the leather/clothing is out in the open. Ridges and wrinkles should be given a generous amount of shading, but not so much as a few lines; wrinkles are not huge.
3rd layer: chainmail (this is most commonly worn under 4th layer plate mail. Some parts of chainmail are shown, some aren't. For parts that aren't shown, give moderate amounts of shading, gray to dark gray, since the 4th layer plate is bulky and covers the parts.
4th layer: platemail (general armor worn by knights. Give less shading in areas where there are light sources given off in that general direction, where as sections where there are no light sources to give strong amounts of shading. Give shadows looming over the corners of the breastplate if the shoulder plates are big enough. Give complete shading [if the knight is wearing a helmet] over the eyes, unless if given a camera's close up.
Now, this is a basic run down of what would be needed. I'm tired, and as such cannot concentrate enough to give more information. Hope this helps you further (even though you didn't reply yet XD)