Before setting out on your endeavor, pick your pencils. I chose an HB pencil for sketching, a B pencil for dark lines and dark shading, and a 2H pencil for light shading.
Start out with a clean simple sketch of the horse's head. You can use the guidelines as reference. Make sure that your lines are light/ easy to erase.
Once you have your sketch, you'll need to go in and define your outline and features a little bit more. Pay attention to the way the outline curves. You shouldn't have any straight lines.
I chose to shade i my background just to make the horse pop out a bit more. You can do this using a tissue and a soft, dark pencil.
Further define the outline using either a 2H or an HB. try to blend the outline into the background. Again, it's pretty important that your lines curve in the right places.
Now, using the 2H pencil roughly shade in the shadows and hair. This will make it a lot easier to complete the next steps.
Work your way from top to bottom with your shading. Use the 2H for your light values and the B for dark values. Let your hair lines flow naturally, not too straight and not too hectic.
Shade in the horse snout. The toughest part about this will be shading in the muscle bulges. Stick to using your 2H and B for shading and you should be fine.
Now for the mane. Use the 2H to draw in dark strands of hair. Don't worry about lighting and detail yet. Just make sure that your hair is flowing naturally.
Finish up the drawing by defining the mane. Use a B or HB pencil to add dark strands and to blend/darken the mane. Use an eraser to get the shiny look that the mane has. With a little clean up here and there you should be able to call your horse done! I hope you enjoyed this tutorial or at least learned something new!