I've just made it to the volbovo islands (East island, near the volcano, island above the snow continent) and i think this is a good point to compile and share some tips of my own. (Warning,incoming wall of text)
The two most useful towns for buying ingredients in making foods are Chapoor town(desert town,northwest,2nd island you go to), and Alal Market(South island,where you find Ninya, the wind girl).
You can buy a 5* chicken from alal market ,a 4* bread from Amajura coastal south - sea house (bottom right of the west island)
and simply make a forest salad (Lettuce,tomato, and pumpkin. Lettuce and tomato can be bought at chapoor town, and the shike-pumpkin is bought at your starting town), combine those three ingredients, and make a easy 11* dinamic sandwich (i think this should be translated to dynamic sandwich? engrish. heh.) Here, you can start mass producing one of the best foods in the game,giving you hp up,attack up,and defense up with NO negative stats.
Stock up on 5* forest barbeques from Alal market. 95 stam. Best and highest stam food until you can start making those heavy ramen out of lard meat farmed from the fat pigs in the snow island(but you can't mass buy the lards,sadly).
As Hajtand pointed out, stock up on 4* eggs,bought at the Cankara west coast sea house (2nd island, at the bottom of the island).
You can also stock up on 3* milk located in the Elp's village (where you find Une). Useful for many recipes or even turn the milk into cheese via fermentation barrel.
a VERY powerful food is the espresso,coffee latte,cappuccino,and soycciono. Guess where you can mass-buy coffee beans at? Alal market. +1 sp at the start of every battle can make the difference between your hero just spamming lightsabers and clearing everything in your path. If you want one without negative stat buffs, buy and stock up on the roasted octopusquid located in the Tropeanya islands, the remote sea house located by taking the boat from the SamaSunResort. Cook the roasted octopusquid over a fire and make dried squids.
Tadaa! you now have a go-to combo of Forest barbeques,Dinamic sandwiches, and dried squids for travelling everywhere. However,you need to have weather considerations...heat and cold will drain your stamina fast even with good food without the proper ones to negate the stamina drain.
For cold weather,and EXTREME cold weather, you'd need 1 hot food to counter the extra stamina drain brought by cold weather. TWO HOT FOODS for EXTREME cold. This is important if you want to make it to level 200 of the ice dungeon without running out of food.
You run into hot and HEAT weather early on,infact, on the second island- the desert. The nights/morning are also cold, so you'd need TWO cold foods and 1 hot food to completely negate all extra stamina drains brought by respective weather. The other place where you'd have to bring two cold foods is when you reach said volcano, the firefly cave near the volbovo island.
(hot and cold adds +5 stam cost to all actions, and heat and extreme cold adds +10 stam drain to all actions. All of a sudden your normal travel of 10 stam drain will double to 20 if you travel in heat/extreme cold without any proper foods!)
Two level breakpoints i've noticed: level 10 and level 35 will let your characters start with 1 and 2 bp at every fight, respectively. These levels are good breakpoints especially for your main hero, and using a +1sp food,enabling usage of lightsaber or lightsaber advanced at the start of every fight. (I forgot when my hero learned lightsaber advanced...i think it was level 45 or 50.)
Also, as Hajtand pointed out in a previous post as well, not all weapons are created equal. There is one particular weapon that is all around powerful and useful. The needle flail. You buy it as early on as the third island, in the elp village, where you find Une. 30 attack and 40 matk. Infact, on the same island, infact,you can make said weapon with materials (Iron ore,Silver Ore, and emerald) that you can gather just in the rocks to the west of JimeJime camp. This weapon is SO good that i'm still using it all the way to the ice caves. Just craft it using all 3* or higher materials and you're good to go for a good first half of the entire game.
A relatively good defensive shield is the Gorgeous shield. You can start making these in mass once you reach the Alal market,since you can buy gold here. You'll have to settle for the 1* gold ore to make these shields until you venture into the Alpas mine, which is ironically on the same island. Using other higher star materials (i did all 5* and over),however, you can get 30-80 hp,15-50 def AND mdef, and a little bonus magic attack to go with it. Again, easy to mass produce for all your characters.
Finally, if you're still having trouble, you can always make some all-revival-healing-sp potions. I generally don't use items until boss fights though. (Be warned this method is VERY expensive.)
Guess what you find in the Alal market? Moon grass(applies effect to all when mixed in potion), Angel flower (revive), piece of courage (+1 sp). Get some potions (60 or 80 hp, i just bought some of the 80 hp potions from the first house you travel to in the snow island, the south sea house), mix all 4, and you'd make a small mixed potion that heals all 80, revives all, and adds +1 sp to all.
the trick however, is to take that mixed vial, Mix AGAIN with another healing potion, piece of courage and healing grass.
it then becomes a medium potion that adds to the WHOLE party: +191 hp,2 sp, revives.
mix it AGAIN and it becomes a large.
if you mixed it with ANOTHER small mixed vial with the same stats,another healing potion,and another piece of courage...
you make a rediculous large potion +4 bp, +350 or higher hp, and revives. Pretty much a full party revive and sp steroid potion.