Use your title to say what the app does
Apple lists your app's title among the text App Store search matches against. Put the plain phrase people would search right after your brand — “Brand: Habit Tracker” says more than “Brand — The Best Way to Build Habits”. Neither store publishes how word order within a title is weighted, so treat a change as a test: note the date, then compare that phrase's tracked rank two weeks later.
Extra iOS localizations: a keyword test, not a trick
Apple's localization table lists the languages each storefront supports: the US storefront adds Spanish (Mexico), French, Korean and six more to English (US); English (UK) is not on that list. ASO practitioners report that keywords in those extra localizations can also match searches in that storefront. Apple doesn't document it, so treat it as a test: write real copy in that language (people who use it see your listing), add only relevant terms, and track them separately.
Start with keywords you rank 11–30 for
If you already rank 11–30 for a keyword, the store already returns your app for it, which makes it a sensible first test. Give one of them a place in your title or subtitle, note the date, and compare its tracked rank over the next two weeks with keywords you didn't touch. Some will move and some won't; the comparison, not the tactic, tells you which.