I'm also new guy, but I can give you some opinions.
As for normal battle, we normally put the TC outside and secure the food and gold. As for world war, we will need to secure the TC in order to reduce the star got by your opponent.
Crown, mostly are for late game I guess, you can retrain your troops with crown, so that you can launch plenty of attacks in a short time. Crown is a must to change your nation, it cost 600, so you might want to save it, if you are plan to change your 1st choice nation.