The best option in this game to get resources is to grow "Dazzling Mana" (all magiminsm at 42) in slimes for the first time:



These little helpers multiply it by 2!
It is profitable to feed each slice up to 3 times. Any more than that is not profitable. Look at the green slime, he's fed 4 times, but we won't get an extra resource:


For example: 3 x Dazzling Mana for each slime 2 times a day. We end up spending 36 Dazzling Mana (3DM x 6 slimes x 2 times/d) and get 72 pieces (36 x 2)!


We can end up using them on almost any kind of resource, one Dazzlin Mana at a time, which will multiply the amount of resource in the slime by 3-6:

Each resource has been enhanced with one mana.

Of course you won't be able to do it right away and you'll have to start small, but it will pay off :)

PS. You can also try to find another resource with more magic, but Dazzling mana can be used in any slime without losing time.