Gummi Ships

Making a reliable Gummi Ship is relatively simple. Rely on the first few pieces you pick upto make a decent fighter. Don't bother with excess things like esuna and gravity (or whatever it's called) which don't really do much.

Any other suggestions I missed?

Osmose is useful if you are using lasers rather than cannons, as it lets you draw in power for the lasers from all across the screen. It's also useful for restoring armor and shields. Shields are a lifesaver, and the Full-Life Gummi is also handy, especially if you don't like the Gummi Ship battles. With Full-Life, Shields, Haste2, and decent armor, you can get through even the toughest battles without firing a shot. Weapon-wise, I suggest using Thunder Gummis, due to their awesome rate of fire and infinite ammunition. Thundaras are nice for wiping out things on the sides of your ship, but they don't fire straight ahead. Don't bother using the Blueprints you get from the enemy ships, as most of them need to be modified to fly, and none of them are very good. Just build up your own ship using all the best Gummis you have. Also, remember that your ship can have multiple parts, all the blocks don't need to be touching. Oh, and don't forget to customize your ship's paint job! ;)

Hmm...I agree with you, Skyblade. Especially about the paint job part. Even once you get all your weapons and stuff down, if you don't like the look of your gummi ship, you will be less inclined to like the battles, in my opinion. I mean, who ever wanted a good RACING muscle car if it didn't LOOK good?

I think that the Cid and Squall Gummi bluprints are acceptable designs as to their looks.
The Aerith and Yuffie scared me.