Try to destroy an enemy ship's reactor. It will not be able to shoot at you without power. If you cannot take out their reactor room, consider the enemy crew;s placement and its shields and weapon. The crew on your opponent's ship acts like an extra shield. They will force you to shoot a particular room more in order to destroy it. If you cannot take out their Reactor room, aim at your opponent's weapons and take them out. However, if their shield room has crew inside, you will have to take out them out first. The number of green bars on each room determines how many shots will be needed to destroy that room. Once the room is destroyed it will decrease the ship's overall health. When defending your own ship, there are two different scenarios. They are PvP attacks and missions; or when you are prone when not actively playing. When logging off, leave crew members in vital areas such as the Reactor room, Shield room and Weapons room. Consider having the majority of your crew members in the Reactor and Weapons room for best results. You might need to repair rooms when you attack another ship. Your crew will not die when shot at, and they will repair the rooms they occupy. Always start a battle with at least one crew in the Reactor and another in the Shield room . Then have one crew member with your fastest weapon. If your enemy targets a room that you want repaired, move your crew to that room if possible. You can only move one crew member to a new room once during combat.
Crew
You can still recruit crew members even if your ship does not have enough beds for them. Get new crew when you have some extra minerals to spend on them. This will allow you to get the best possible stats for crew members when you unlock new beds for your ship. Better crew members are rarer, but you still must view their stats to determine if they are truly required for your ship. Each crew member has different stats (Pilot, Shield, Engine and so on), making them a better or worse choice for the corresponding room.
Resources
Collect as many resources such as Minerals and Gas as possible. Use them to build and upgrade your ship as soon as you can. Obtain Gas Collector room followed by the Mineral Storage room to allow you to store more of those resources. Complete the missions (Explorations and not the green highlighted ones) to get more resources for improving your ship.
Upgrades
All of the rooms of the starship are important, but a few are mandatory. Besides those needed for resources, concentrate on the Reactor to maintain more energy during fights, the Shield, and Weapons.