Typing fast is very difficult in the default keyboard and gboard

OneUI tips

Night Mode (in Settings > Display)

Full screen gestures (in Settings > Display > Navigation bar). Disable gesture hints if you don't want the bars at the bottom.

Lockdown mode in power menu (in Settings > Lock screen > secure lock settings > show lockdown option)

Always on Display is tap to show for 30 seconds by default (change in Settings > Lock screen > Always on Display > Display mode)

Only notification icons are shown by default on the lock screen (change in Settings > Lock screen > Notifications from Icons only to brief or detailed)

Show all notification icons and turn on battery percentage (Settings > Notifications > status bar)

Turn on Stay on lock screen for Intelligent Scan, Iris, or Face recognition (Settings > Biometrics and security)

Lift to wake (in Settings > Advanced features > Motions and gestures)

Adaptive battery (in Settings > Device care > Battery > three dots at top right > Settings)

Samsung keyboard theme adapts to theme of current app (light/dark)

Scene optimizer (in Camera > Photo > swirly icon at the bottom right)

If navigation bar or gestures are turned on with hints, swipe from the home button to the right to switch to the previous app, or swipe to the right and drag left and right to scroll through recent apps

If gestures are turned on, swipe up and hold from the home button area to launch Google Assistant

In recents menu, touch on an app's icon to get the split-screen and popup-view options.

Credits: https://old.reddit.com/r/GalaxyS9/comments/alkihz/just_got_the_oneui_on_my_s9_any_tips_or_tricks/efeu2j1/

/r/GalaxyS9 Thread