a blind trick i learned about laying out a line with a string is not to start the string at the corner of your house but to run the string starting from a point along the wall as far back as you can. its easy then to make sure the string is equal distant along the wall then when it passes out beyond the corner you can maintain a nice straight line out from the house.
stake down the far end of the line then go back and feel that the line stays straight along the wall. you may have to move the far stake left or right till you get it just right. dont know if this is clear, it's real easy if i showed you but maybe not to explain.
