One of the most avoidable mistakes you can make when sealing pavers is not cleaning the entire paver in corners, edges, around poles, etc. These areas may not be visible until after you've sealed the pavers- and then it's too late!
To avoid this potential issue altogether, a good way to start your cleaning process is to wand all the edges, corners, and areas where the surface cleaner may not reach. When surface cleaning, make sure to overlap on each pass, and "cross wash" the area, by repeating the surface cleaning process in the opposite direction.
Not only are you making 100% sure there are no missed areas, you're washing the pavers twice as much as the competition. Customers understand doing a quality job and want the company who will get their pavers the cleanest, so make "cross washing" a selling point of your process.