Whenever playing an online match, running up to an enemy castle will probobly get you killed. You'll require some decent strategies if you even want a chance to win. Here are a few.
Worker Rush[]
Have about 5 people on your team become workers, everyone else can be whatever they want. All workers rush to wood and mineral resources with everyone else covering them. If all goes well, you should be able to get enough minerals and wood to upgrade 3/5 of your base or more.[]
Bomb sneak attack[]
This works amazingly on the Sugar Cove map. After upgrading the Worker, utillizing the big bombs, sneak across the map, into the enemy base, then go crazy.
All-In[]
This is for mid-to end-game. WHen your whole base is upgraded and your butchering each other, its time to go on the offensive. Launch an all out attack from all possible angles on the enemy castle (or ship or goal, depending on the map). Use this only if your confident you can defeat your enemies quickly. A drawn out assault can be very costly and allow your enemy to regroup.