Whenever I am setting a long length of deck posts, I use this method to make it easier to quickly and accurately get the posts plumb and perfectly aligned with each other. I start with the corner posts, bolting them to the framing using blocking and shims as needed to make sure they are both perfectly plumb in all directions. Then I attach a pair of strings to the posts, one at the top and one at the bottom (as shown in the drawing), and mark the layout of the middle posts on the strings with a magic marker so that all the posts will be evenly spaced. I then put away my level as I use these strings as a guide when installing the middle posts. The layout marks on the strings ensure that the posts are plumb from left to right, while the strings themselves ensure that the posts are plumb from front to back. I have found that this method is a lot faster and more accurate than leveling each post.