Second, be specific. Third, share your feelings about their work. Tell people how good you feel about what they did that was right, and how it helps the organization and the other people who work there. End with a reaffirmation and encourage them to keep up the good work. Remember to praise progress even if it is only approximately right.
Perfect behavior is a journey that happens one step at a time.
A manager's job is to manage the progress toward the goal. A good manager thus constantly looks for opportunities to praise progress or to redirect. You have to hold them accountable. The first alternative for poor performance should be redirection, which means going back to goal setting trying to find out what went wrong and getting them back on track. If you are dealing with somebody who knows better, who as performed a similar task well in the past, then a One-Minute Reprimand might be appropriate.