First five hours

In your first 5 hours with Boom Beach, after the incredibly brief tutorial, you will want to ensure you concentrate on building up your supplies of resources, and exploring the game map. There is little point in devoting too much time to defense at this stage, as there are only a couple of buildings you can construct for that purpose, and you won't have too many resources to protect.

You can get lots of free Diamonds by exploring the game map early on, so use what Coins you have for this purpose, as well as to train up your first few troops. The next few hours will be spent attacking the AI players who you encounter on the map. You should also aim to level up your HQ when possible - this will take time, but you can afford to spend some Diamonds on this if you want a quick fix. Whenever you explore a new section of the map you are likely to see a treasure chest - these frequently contain Diamonds.

In short, you should make sure you have built all the structures available to you, leveled up your HQ if possible, and explored the map for some much needed resources. Don't forget to chop down some trees as well!