Ulite: Upgrading your ship
Most important thing you have to have onboard is an escape capsule. It brings you to the next public station if your ship is shot down. Otherwise you will be killed. That dosent mean the game is over, but you have to restart again. All the experience you earned so far will be lost.
The next thing you should buy is a better gun. Connect it with a laser cooling booster, so you can fire much longer with full power.
Your ship should have at least one scanner. It is recommendable to have up to three of them onboard. They will help you to pinpoint the enemy. Your shots will be more precisely.
Then there should be shields on your ship. As more as better. Shields prevent your hull of being damaged by the enemy. How much shield you can use depends on the defensive skill of you and your crew. It is recommendable to connect the shield with one or more energy booster units. They will recharge the shields, so they can protect you better.