Putting down some guidelines is a good idea as well to help line things up. You can put the guidelines on a separate layer so that you can easily delete them later (image 5, 6, 7 & 8).
I try and work zoomed out as much as possible when I am painting, that way I can see the entire composition and I don’t get bogged down too much in details. Even when I am working on the fire escape I stay zoomed out to about 25%. The lines may look fairly straight, but if you zoomed in you would see that they are not. What people usually don’t realize is that it takes me several attempts to make the line I want. If I put down a stroke I don’t like, I undo and try again until I am satisfied by the line I made. I try not to use any straight line tools just because it makes things look too perfect and too mechanical (image 9 & 10).
