Draw the lines keeping the Church’s walls in mind. The lines of the walls will start straight and end in a slope depending upon your design in mind.
You may use stencils for drawing perfect shapes or just make triangle from the sides of a rectangle.
If you are not very proficient with coloring you may use crayons or pencil colors and make very light strokes. As you color, you may play with the light and darker colors. Remember that you can vary the pressure and create a lighter or darker color using the same pencil. To make your drawing more realistic, keep in mind light, shadow, and contrast. A hint to color well is to assign an area where light falls. Like sunlight will not be alike on the east and the west. Hence, one side will be dark, another will be lighter.
Start with lighter layers, and add more if you need to make the area darker, or add one color on top of the other to create a different tone.