Research a variety of graffiti styles. In order to gain a good understanding of graffiti, it is important that you familiarize yourself with as many different arrow compositions as you can find. Browse the Internet or buy a book of graffiti, and look at the variations in size and style. This will help you decide which parts you may be interested in replicating, and will inspire you with your design.
Sketch out your arrow on a piece of paper. At this stage, it is important to keep your arrow simple. Start by drawing your arrow in its most basic form--as a collection of single, straight lines. Try to concentrate on the sizing and shape of your arrow. Put the graffiti style to the back of your mind until you develop your arrow.
Draw a larger arrow around your simple sketch. This larger arrow will form the basis of your graffiti design. Feel free to draw these exterior lines in any style that you want, this step is simply to help you to begin to build up your design.
Convert your arrow to graffiti style by adding some detail. Thicken the outline to make it appear bold and help it stand out from the background. Color is an important element of graffiti as it can bring a design to life, so look to implement color into your arrow, while taking care to not make your design too garish. Try adding some shading to create a 3D effect.
Practice drawing your design. Work in your sketch book until you feel comfortable drawing it.