You will need Energy to fight through missions in the Campaign. Energy is obtained via completing daily quests (you can receive energy three times in a day) and leveling your team.
There are several ways to gain Gold and Emeralds - complete the daily quests and storyline quests. You will receive some Gold after finishing each mission in the Campaign.
You can also exchange your Emeralds for Gold and Energy (the number of refills depends on your VIP level).
Friendship Chips are received from your ingame friends. You can collect up to 15 mails with 30 Chips each per day. There is also a daily quest - send gifts to your friends and you will receive Chips for completing this quest.
You are rewarded with Arena Coins for your Arena rank once a day. You also receive them for 5 first attack repulsions on the Arena every day.
Tower Coins can be looted from chests in the Tower and as a reward for earned Tower Points. There are two storyline quests which grant you Tower Coins as well.
You gain Grand Arena Coins with time. Amount of given coins depends on your rank on Grand Arena.