Really, the only way to get a higher score is to get the items quicker. Since the items are set out in a random pattern, it's actually possible to get a high score if you play long enough. If you're going for the trophy, aim for getting all the items in the first level before the second time bubble disappears, all the items in the second level before the third bubble goes, and just keep your fingers crossed for the last level. (It's actually possible to get all the first level items before the first bubble runs out, and all the second level items before the second bubble disappears.) If you miss either in the first or second level, just restart. There's no way to get enough points to get a trophy.
Hope that helps.