These are a few to get you started.
1. Back up all your contacts with your iPhone to Google. That way when you sign in with your S7, contacts will automatically sync in.
2. If you need to back up anything else from your iPhone, you can use the Samsung SmartSwitch app on your Mac or PC.
3. Hold your finger on an empty part of the home screen, swipe left and turn off Upday or Flipboard. This will just make things quicker.
4. Go to Settings > About Device > Software Info, > and then click on build number 5 times.
Then go back to Settings > Developer Options, and change the following to 0.5x instead of the default 1.0x. Everything will be quicker.
Window Animation Scale
Transition Animation Scale
Animator Duration Scale
5. Go to settings, then themes, and search and install the Android 6.0 theme.
6. Download and use Chrome.
7. Hold your finger on the stock browser in your app draw on the home screen, and slide to trash can. Then slide Chrome (and anything else you want) in.
8. Hold your finger on an empty part of the home screen, then click on screen grid, and choose 5 x 5.
9. Download and install SwiftKey.
10. Go to Settings > Display > Screen Mode > and choose Basic. This is the most accurate mode.
11. Make sure in camera settings, you have double tap home button to launch camera on. This is the quickest way to launch your camera, even whilst your screen is inactive.
12. If your phone is connected to Bluetooth in your car, go to Galaxy Apps, search Samsung Music and then download it. The app will be called Music, and it'll look like an orange pair of headphones. Use this when in your car, as you will be able to change tracks with the controls on your steering wheel.
13. If you listen to headphones or earphones a lot, I recommend downloading PowerAmp. It's the best music player out there for phones.
14. Turn off GPS and Bluetooth when not being used. Easy to do by sliding down the settings tray from the top of your screen.
15. Slide down settings from the top of your screen, then slide down again, click edit, and turn off Quick Connect. Now you have more space for notifications.
16. If you're using fingerprint scanner, register the index finger and thumb of both your right and left hands. It'll be useful when you're using it on the other hand, or its lying flat etc. You can register up to 4 prints so it'll be enough.