Attach a support clip high up on the fascia board, at the opposite end from where the running outlet will be. You will probably find it easier to tighten screws near the roof covering with a hand-held screwdriver rather than a power drill-driver (image 1). Position a clip at the other end of the eaves, lower than the first and at the correct height to give the necessary pitch (image 2). Tie a string line between the two clips to form a guide line (image 3). Make sure the string line is taut and is not caught anywhere, especially if it has to travel around a corner (image 4). Check the pitch with a level (image 5). If it is not as you want it, adjust it by slightly repositioning the lower bracket.