Suggestions

It's very hard without a Ribbon, but creative use of the Added-Effect Materia in your armour can help make up for it.

I find the Aqualung enemy skill very useful, it's surprisingly powerful!

A little MP heavy, but that's what Ethers are for.

You can get Aqualung from the Harpy creatures in the Gold Saucer desert area (on the world map) which is useful before you fight Jenova in the Ancient City.

Of course you need to already have done the Gold Saucer part and obtained the Buggy to be able to access the desert area of the world map.

(PS - Aqualung is also quick and easy for defeating the two Turks at Gongaga.)

how much mana does Aqualung consume anyway? :p i typically used Trine for its dmg divided by cost ratio..