[BEGINNERS WAR TIP #2] watch replays of previous war attacks![]
The most powerful thing you have at your disposal is the replay from the best attack against each base. Remember that the enemy can no longer make changes to their War Base or their Clan Castle, so whatever traps and troops you see in the replay are what you’re going to get during your second attack. You can often find out where their Hidden Teslas are, for instance.
If you see some powerful Clan Castle troops, you might change up your strategy somewhat to deal with them.