Drawing a horse for the first time can seem challenging and arduous, but when broken down into simple parts, your squiggly lines will transform into a horse with ease, right before your eyes. If you are not familiar with how a horse looks from memory, find a reference picture of one, and draw from that. All you will need is a sheet of paper, a sharp pencil with an eraser and a burst of creativity to get you started.
Start your horse by lightly sketching the basic shapes of the horse's entire head, body and legs, minus any details. Think general and simple shapes such as rectangles, squares, triangles and circles. I use a rectangle for the head, triangles for the ears, a cylinder for the neck, an oval for the body, cylinders and circles for the legs and knee joints respectively, and small squares for the hoofs. You may use whichever suits you best, but this is a very important step to ensure there is enough space on your paper to draw the entire horse correctly. You may be very disappointed if you put the effort into details of the upper body without leaving enough room to draw your horse's legs. Again, be sure to sketch very lightly, as you will be going back in to erase these lines once you are complete.
The most important details of your horse exist in his/her head and face simply because it allows the most unique and subtle details and characteristics about your horse's personality to shine through. Give special attention when you draw the angle of your horse's neck and head, the direction of its ears as well as the expression in its eyes. Try to replicate what you see. Fill in the details of your horse's head by drawing in slanted ovals for the eyes, circles for the nostrils, and then trace in the outside shape of the mane and tail. This portion should be fairly easy since the largest shapes are basically done.
Now all you have to do is go back in, add detail as you see fit, and erase whatever lines you do not want. It is really that simple! The key is to build your horse up with layers, increasing the detail until you are completely satisfied with your work. Work slowly and with a light stroke. There is no need to rush the process. The more you practice, the more perfectly drawn your horse will become. Good luck!