The seahorse looks like a complicated character but is really just a combination of circles and wavy lines. Start by drawing a big circle for the head and a smaller one below it for the tail. Add some curved lines between the two for the body.
Let's do the tail first as that's the tricky part. Follow the picture by drawing a spiral shape inside the smaller circle.
Next erase the some of the lines of the circle you no longer need for your tail. Then draw in a wavy line all the way down the back of your seahorse, from head to tail. This will become its fin.
Add a smooth rectangle will make the snout - remembering the upturned nose. Triangle shapes on either side of body will become the seahorse's flippers.
Next to add some detail and character to the face. Draw a large oval for the eye, inside that draw a smaller oval, you can also add a tiny dot for the very inside of the eye if you like. A few lines on the flippers and our seahorse is starting to take shape.
Time to give your seahorse color. Add some shading to the fin down the seahorse's back. You might like to split it into two just like the drawing. Colored spots on the head and tail look like scales, two small circles for nostrils and some more shade to the fins.