Currencies

There are three types of currencies in SimCity BuildIt:

1. Simoleon - The main currency in SimCity BuildIt. You can obtain it by trading, upgrading residential zones, and completing shipping orders.
2. SimCash - This is the 'special' currency in SimCity BuildIt which is used to speed up the production timers. It also can be converted to Simoleons. SimCash can be obtained by completing achievements and via In-App Purchase.
3. Keys - This is obtained only by completing shipping orders. One key per completed shipping

Mindset

First of all, this game is nothing like the old SimCity or Civilization. Especially if you don't want to pay a single cent playing this game.

Sure, you can make it sort of like the classic SimCity to bypass all the timers of production and upgrade. But to do that you need lots of SimCash which will cost you a lot of real world money! Electronic Arts will happily sell upward of 99USD for a SimCash package. 

Many people cry out that this is such a scam but it's still perfectly playable without purchasing any SimCash. The trick is to treat it as a long term game. Think of taking care of a virtual pet like Tamagotchi for weeks and not playing a board game on one Sunday afternoon.

If you are keen to take care of this city like a pet for the long term, then this is the game for you. If not, you are better off with many other game. 

As of now, my city is at level 11 with 60,000 population. Services unlocked include Education, Transportation, Power, Water & Sewage.