Former American vice-presidential candidate Sarah Palin's memoir has sold 300,000 copies on its first day, among the best openings ever for a non-fiction book in the US. Going Rogue was released last week and its print run has been increased from 1.5 million copies to 2.5 million, publisher HarperCollins has announced. Palin, the ex-Alaska governor and 2008 Republican vice-presidential candidate, is in the midst of a US-wide promotional tour.