This list should help anyone in the 35-40 level range. The areas may seem a bit low, but remember, you're going for maximum kills per hour to get items. No point in fighting crawlers in Rolanberry at your level because you'll have to rest after every second or third kill.
LaTheine, Konschtat: Elementals, Tremor Rams/Battering Rams, Mad Sheep, Beastmen for the gil and armor drops
Tahronghi: Mandragora for saruta cotton, killer bees for beehive chips, canyon crawlers for silk thread, yagudo for necklaces (bring a stack or 2 of wind crystals. Yag necklace + wind = 3 grass threads. Level 0-1 Clothcraft), gil and the occasional silver beastcoin, elementals and Dhalmels for giant femurs and skins.
Valkurm: Lizards for lizard skins. Be nice to the low levels and farm up near Secret Beach, leeches for beastment blood
Buburimu: Sylvestres for cotton, crawlers for silk, dhalmels for femurs and skins, leeches for beastment blood
Jugner: Fungi for sleep/dance/woozyshrooms, leeches for blood, tigers for fangs and skins
Pashow: Marlboro for marlboro vines, Elementals, fungi for shrooms, bees for chips, quadav for armor and gil, leeches for blood, goobue for moss and tree cuttings
Carpenters landing: fungi for sleep/dance/woozyshrooms, beetles for beetle jaws, elementals, if at the southern entrance, you can camp Orctrap while you're doing this, though he might be a little to high for you
That's not a 100% comprehensive list and depending on your server's economy it may or may not be worthwhile to farm those items, but it's a start.