Aquaria

• Combined keyboard/mouse controls will save you lots of stress. 1-0 keys are shortcuts for forms and shield/bind songs, keyboard navigation + mouse aiming is very good for boss fights, while mouse-only navigation is better for jumping off-wall (especially in a certain location, you'll know it when you get there).

• Explore, explore, explore. If you find an area/boss too hard, go elsewhere, get upgrades. The game is very lenient towards sequence-breaking and a few forms/upgrades are entirely optional, so search around.

• Big red bulbs are the only finite cooking ingredient, everything else can be found/farmed, so don't be afraid to experiment. Different kinds of meals have similar forms, so if you find a new recipe for one thing, try using the specified additive for other similar stuff. Poisonous meals are mostly useless, sealoaves aren't.

• The useless-looking charge attack of
  nature form
  is for launching yourself off a wall if you aim it where you're holding. Again, specific use but it will save you lots of stress.

• Don't be afraid to backtrack to a save crystal when low on health, you can die surprisingly easily.

• If you're having trouble with bosses, cooked stuff will help a lot. You want: healing (at least Heal 2), +defense, +speed, +energy shot, cure poison if applicable, all else is optional. Don't hoard stuff, you can get more and the maximum is 8 anyway.

• The Aquarian script is actually English with a different font. You can translate it yourself or replace it with a different file, I recommend it as the messages don't spoil anything but add more understanding of the game world. Original is gfx\aquarian.png, English (ugly) is aquarian_alt.png, here's a much prettier "bioluminescent" high-visibility Aquarian-looking English font.

• If you find a passage locked/blocked/that looks like it requires some future upgrade, mark it on your map! Similarly, mark good resource farming spots with a different color.

• There are secret passages (where you can go through walls). You can find them on the minimap (but not on the main map!). If you see a suspicious passage that's not appearing on the main map nor the screen, poke around. Some secrets may require different mobility upgrades.

• Some treasures are ornamental, but some are actual upgrades for your home or your armor (in particular the
  jellyfish armor
  is awesome for exploration and slower boss fights).

• Don't stress in the final location, the last save crystal/transport point is right before the last boss, so there's no point of no return.