So, the best way to earn coins, is to provide economic growth, ensuring more coins will be available to you in the future.
Nobody liked that , really, and we got the “coin machine” 
Anyways I often post links to this thread, and the OP has links even further back. The only info in this thread that is out of date is the prices regarding refined gleam and gleam doors. While much of the conversation is people being pissy about the doors, the thread has a ton of other good info in it:
There are very few “raw” blocks or materials you should throw directly in the minter, if you want coins from it. Corruption, growth, maybe sponge. Thorns, a couple of other natural blocks pay well. And they all also drop desirable loot. The thread linked above has some numbers for corruption. Here’s a more recent breakdown on some growth farming, now that we can have awesome, low level growth farms:
There are some other items not frequently mentioned. They’re not hard to discover. First thing is browse knowledge across categories and look for items that mint for substantially more than similar items. These are often the minter “easter eggs” and they will eat up some resource that’s common helping to keep the severs from being flooded or something 
Check out soups and broths. There’s an item there that’s way out of order. If you have a bunch of that junk around, pick up some cash.
For the most part, it wants processed items. If you’re thinking you need to be high level to have the stuff, it starts right at the beginning. Here’s one of the first/easiest crafted items:
A foliage mints for 0.05c and there’s not much else to do with it, some basic recipes and decor. You would need 20 of them to mint for a coiin. 36 of them are worth 1.8c
A trunk mints for 0.05c, same as foliage. You can use these to make some doors, for better coin. But anyways 36 raw mint for 1.8c.
36 trunk (1.8c) + 36 foliage (1.8c) = 50 warp conduits. Warp conduits mint for 0.6c. So a few seconds at a table, and your 3.6c of trunk and foliage became 30c, and that’s before coils, which (0.30 X .4) gives you 42c.
Sell them on stands. I used to sell trunk for .1c OMG found out I was selling cash literally.
5.4 coin to toss those mats in the (fully coiled) minter. 42 coins to pass them through a table first.
~700% more coins?
EDIT: Also in terms of what people mean by simply trading using BUTT, here’s an example that came to my attention this week. Some of this got cleaned up already but this will do for a small example.
There’s 7200 coins for moving half an inventory of items a few meters on the same planet. Could be the other side of the planet IDK. I’m pretty sure that there was a large amount being sold for 3c earlier this week, someone got that.
Request baskets are the bane of this economy, IMO. However they’re constantly creating trading opportunities. At least there’s some give and take to it.