Random Battles has a pattern that it goes through because 12 players on each side is a lot.
Early Game - Trading:
Because there are some many ships, the first several minutes are focused on trying to deal damage to the enemy while taking as little as possible in return. Usually this means finding a safe position or staying well-angled to incoming fire and trying to be very accurate with your shots.
If your team wins the "trades" (damage for damage), you will start to sink enemies or drive them off... then your team can move up and claim the space being fought for.
If your team loses the "trades", you will start to be pushed back as you lose teammates and health. The enemy will use their superior health to force you into unfavorable positions.
Mid-Game - Claiming/Cedeing:
As stated above, in the Mid-Game you have to make decisions based on how the first few minutes went.
Are you ahead? Can you capitalize on being ahead?
Are you behind? Can you find a place to be safe and turn things around?
Is there a daring play you might be able to make to alter the situation somehow?
As both sides lose teammates, options start to shrink and your decisions become harder to make.
End-Game - Finishing/Desperation:
With few remaining ships in the waning minutes of a match, it's down to the few remaining.
Are you ahead? Keep the lead. Don't throw it away.
Are you beind? You likely have very few to no real options. Do your best~
In truth, our game is deceptively complex and can take years and years to master. Everyone starts out just being in a boat and trying to land some shells, but the more you play the more you'll understand the larger game going on behind the scenes.
If you're ever just in the mood to blow some stuff up, Co-Op is great for a 4-5 minute "Get in and blow stuff up!" gameplay session. Random Battles is a longer game with all the phases mentioned above.