Choose a real-life flower or a photo of a flower you would like to use for the tattoo. To begin the drawing, you need basic art equipment and Internet access. Learn to draw a basic version of that flower by searching online for instructions or quick drawing lessons.
For tattoos, there are certain styles of drawing that are preferred based on the way in which parts of the sketch stand out when transferred to ink and skin. Bold lines and clear shaping are helpful. Consult with other artists or a tattoo artist as you develop your sketch to see which parts of your flower need more or less shading. You can draw a flower for a tattoo in anywhere from several minutes to several hours of time, depending on how much detail you prefer.