1) Same as the iPhone, pressing the digital crown and the contacts button will take a screenshot of the watch face which gets automatically stored on the camera roll on the iPhone
2) Swiping from bottom gives you the glances and when you are on the glances card where you can set the watch to mute, etc. there is a button which allows you to ping the iPhone. When you tap the button, it pings the iPhone, but when you press and hold it, it pings the iPhone along with flashing the camera flash. Really useful to locate your iPhone when it is dark
3) This one is really useful, usually when you are in an APP on the Apple Watch and want to go back to the clock face and exit, you usually need to click the watch's digital crown three times. Once to exit from the APP, once to center the APP view to the clock face and then finally, one more to go back to the watch face. Now, there is a really easy and simple way besides these 3 clicks. When you are on an APP, simply cover the watch face with your palm, you need to make sure that the palm touches the watch face. This will simply turn your watch face off but also exists the APP and put its back to the clock face. Next time when you raise your wrist OR tap the watch, it will show you the watch face. Really cool and very handy short cut!
4) Double clicking the digital crown always takes you back to the last used APP
5) When you are in the weather APP, tap once on the circle which brings your further details like expectancy of rain, wind pressure, etc. Force touching it along bring extra menu items.
6) When you pull down from the top of your watch face, you need the notifications menu. If you wish to clear all of them instead of individual notification, then force-touch that screen. You should then see an option to clear all.
7) Using your Apple Watch App on the iPhone and the APP layout, you can make some cool patterns instead of sticking to the default which Apple provides. You will not have absolute freedom to move the icons where ever you need, as they keep sticking back to the grid, but you should be able to make some cool patterns using them.
8) When you are on the astronomy watch face, tapping the solar system icon brings the planets position view. Tap on it again and it will give you the names of the planets