For the iPhone, you really can't go wrong with the official app. It's expensive for a mobile app, but it's worth it. Keep in mind, though, that using a different app will make absolutely zero difference with your accuracy. If that's what you're looking for, you won't find it. The accuracy is a limitation of the GPS device in your phone (as well as that of the hider), not the app you're using.
Just remember that the coordinates will only bring you close to the cache location. It won't be very often that you'll find the cache at the exact spot your device says 0. Once you get within about 30 feet, stop looking at the device and start using your eyes. Like you already mentioned, the hint can be very helpful, but don't forget the description, title, size, difficulty and terrain ratings. All of these can contain information and/or clues that might help narrow down the hiding spots you need to search.
Edit to add: Welcome and good luck!