As John Dorsey prepares to make a critical decision he knows may shape Cleveland's football fortunes, the Browns general manager spends a moment every day giving himself a pep talk. ''Just make sure you don't mess it up, that's what I tell myself,'' Dorsey said. Dorsey is in the early stages of heading his first coaching search with the Browns, who have been in a futile pursuit of a competent leader for nearly as long as they've been looking for a quarterback.