There are a lot of little tricks to handling chocolate. I like to work on a marble surface because the marble is generally cold, which helps the chocolate set. I also keep my chocolate in a glass bowl, which retains heat well and holds the temper longer. One of the most useful things you can use when working with chocolate is acetate (plastic from the florist). It can be found in most art shops.
To make dark and white chocolate cigarettes: Use a cake comb to create alternating stripes of white and dark chocolate. You can buy one at most cake decorating supply stores. Spread some white chocolate on a sheet of acetate in a very thin layer, about 1/16-inch. Draw the comb through the chocolate to create alternating lines. Return the excess chocolate to the bowl. When the chocolate stripes are firm but not hard, use an offset spatula to spread a 1/8-inch-thick layer of dark chocolate over the white chocolate. When the chocolate sets but is not firm, use a pastry triangle to create the cigarettes. Start about 11/2 inches from an edge and push the chocolate into a roll (it will form naturally). Apply even pressure.
To make chocolate fans: Spread some dark chocolate directly onto the marble surface in a very thin layer, about 1/16-inch. Use the pastry triangle to create fans by pushing the triangle through the chocolate in an arc. Use your finger to hold down one side as you push the chocolate toward the other.