Wood, Metal, Silver and Crops are the harder resources to get in Deiland. This guide will show you how to get so many of these items, you don't know what to do with the excess.
Guide to Getting Resources
To get more wood, you will need a group of trees which will produce pine seeds to plant and another group of trees for harvesting.
Plant about 6 trees with ample spacing between them to harvest their pine nuts.
Next leave a large gap and plant all the pine nuts you have as tightly packed as possible next to the first group of trees. This will be the trees you can harvest.
Once the second group of trees are fully grown (which you will know if they start to drop pine nuts), then you can chop them down and repeat the process. Remember to chop down the stumps as (I believe) they do not grow back.
Alternatively, if your group of trees is small, you can light them on fire to "chop" all the trees at once. This can be done by lighting a torch and moving near the group of trees. If you have a lot of trees, lighting them on fire will "chop" all the trees at once, but you will not be able to pick them up fast enough before they despawn.
Metal, Silver, and Almost Every Other Resource
Metal can be bought. Silver can be bought. Gold can be bought too. Almost every resource can be bought with a few exceptions. As such, there is not much point mining rock in search of these resources, just buy the whole stock of resources you think you need whenever the merchant comes.
Since there are some resources that cannot be bought, such as horns, try not to sell any of your resources except rock (see the gold section).
With coins, you can buy basically everything else.
To get coins, simply mine a ton of rock (your maximum capacity is 999) and sell it to Goliath. Goliath will pay you 2c for every piece of rock. So, if you have 999 rock, you will get 1,998c.
As far as I know, this is the fastest way to get a lot of coins and, consequently, a lot of every other resource.
Image: 20,000+c at the end of the game. Spoilers are the other items that exist in the game.
Result of farming rock throughout most of the game
A Note on Crops
Crops are not as easily bought, but they can be farmed more quickly.
Water speeds up crop growth. Water comes either from your wells or rain. If there is rain on your planet, you can "move" the rain by pressing "R". This will change your perspective to show the whole planet:
When it rains, you will be able to see rain droplets falling from the clouds. Move the planet accordingly with WASD to align your crops to be under the clouds. The rain does not move when you move the planet.
You should now have an excess of every resource. Congratulations!
Now you just need to wait for the characters to visit your planet to progress the quests...