Aquaria

• Combined keyboard/mouse controls are key and 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 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 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.