fire only when needed to keep your super beam charged up. Use the super beam to wipe out hordes of enemies at once.
the more you move, the less concentrated the enemy shots will be at any one spot making them easier to dodge.
Star Beam 2000:
This weapon travels through all enemies in a straight line, damaing them equally. When firing try to hit groups that extend quite far upwards, and shoot in short bursts.
Photon Wave Laser:
This weapon travels through enemies, doing very high damage. However it has a very limited number of shots, make sure you have lined up perfectly for your shot before firing.
When collecting this you are completely immune to harm. Why not make full use of this protection and ram your enemies, they'll die real quick!
How to beat final boss:
This boss is very large, has huge firepower and can withstand a large number of hits from even your very best weapons. The only way to have hope of surviving this foe is to save up the maximum amount of one of the better special weapons. Star Beam 2000 is probably the best. Destroy the turrets immediately, don't worry about the main parts very much.
Once the turrets are gone you will find the boss much easier to handle.