15. It is better to power up your Pokemon after they're fully evolved as it gives you more Combat Power, or CP.
16. You can get a daily bonus (in the form of XP) by assigning your pokemon to a gym. The more Pokemon you have assigned to gyms, the higher this daily bonus will be, and will grant you extra Stardust and Coins. To claim your prize, go to the Shop and click the blue shield icon. Check back every 20~ hours (so long as your Pokemon have not been dethroned) to receive more (the amount may vary depending on how many Pokemon you have in the gym, or their Combat Points).
17. Due to how every item and element of progress is synced with Niantic's servers, when you visit a pokestop, you can simply hit the 'X' quit button and any requisite items will automatically be added to your inventory, meaning you don't have to wait for the animation to stop. People have used this as a means to perform 'drive-by PokéStops', as it's especially useful in traffic. Please only use this as a passenger in a car. Don’t Pokemon Go and drive.
18. That rustling grass animation on your map shows areas where Pokémon are likely to be spawn. It definitely does not mean there WILL be pokemon there, but usually something will pop up if you hang out in that area long enough.
19. The 'game world' is layered
over our own, so fields are fields, rivers are rivers, and so on so if
you're looking for something specific try to go for where you think you
would find it in real life.
20. Some Pokémon only come out at night.
21. Some pokemon can only be found in certain areas of the world. In order to truly “catch ‘em all” you’ll have to literally travel the world. (Unless the heavily rumored but unconfirmed trading feature is introduced in the future)