There are a number of ways to use paper to shingle scale roofs. If you want to see several techniques, read the article on creating the effect of shingles in miniature.
The easiest method is to drybrush acrylic paint onto kraft (brown) paper using a fairly stiff brush You will need to paint an area three times the size of the roof you wish to cover, making sure you have a wide enough section painted to cut into strips that will go across the entire width of the roof. The roughly 1:12 scale shingles shown here were made from one inch wide strips of paper cut longer than the roof I wanted to cover. Cuts were made from the front edge of the strip back 3/4 inch into the strip cutting sections 1/2 inch wide and wider. The first strip is used as a guide for the next strip so that you make your cuts in between the cuts for the first strip.
When you have cut two lengths of paper 'shingles' apply glue to the bottom edge of your roof and glue the first shingle strip to the roof so that the ends of the shingles overlap the ends of the roof slightly. To apply the second line of shingles, run a bead of glue along the base of the previous row of shingles and brush some of the glue back onto the wood of the roof. Your glue line should be about 1/4 to 1/2 inch wide if you are using 1 inch paper strips of shingles. Lay the second row of shingles so the shingles overlap the cuts on the previous row. Position the row so that the loose unglued edges of the shingles are roughly 1/4 inch back of the front edge of the previous row. Adjust this to a spacing you like. especially if you are working with a scale than 1:12. You want the glue to hold only the back, uncut section of the shingle row, the shingle sections should be free to curl and bend a bit.
Continue to add overlapping rows, using roughly the same spacing between rows, until you reach the peak edge of your roof. If you can fit your final shingle row neatly over the edge of the peak, glue it to the edge of the roof as shown above by folding it over the edge, gluing it down, and trimming. If this would make your shingle row too short, cut a piece of painted paper but do not make shingle cuts in it. leave the straight edge of the paper as a 'capping row' and glue it to the previous layer of shingles, folding and gluing it over the edge as shown above. Set the roof aside to dry.