There is more than one technique to use to keep your patty intact. First, If it is too dry, add some water or reserved liquid from the salmon can. Second, finely chop any vegetables (onion and peppers) in the patties. Thirdly, make sure you used enough binder, like egg or mayo. Also, chill the mixture for 15 to 30 minutes before shaping the patties. Lastly, let the first side cook until golden brown before gently flipping the patty.