On this page of our guide to Minecraft: Dungeons you can find information on how to acquire crystals faster. This will allow you to spend more at traders and, as a result, get newer equipment.
In the game, you can sell all the items you acquire while exploring the world. All you have to do is choose the salvage option. A detailed description of best ways of selling collected items can be found on another page of our guide.
On every map in Minecraft: Dungeons you will find various chests. Some of them are hidden as a secret and others have plenty of resources to regenerate your character. It is worth opening all chests available in a particular level to get as many items as possible.
There are a certain number of secrets on each map. You can check it by opening the map.
Secrets can be different and may vary a lot. One secret has a form of entering a dungeon while others are associated with looting chests. Examine each wall carefully so that you won't miss anything.
Looting Crystal barrels
In each level you'll find barrels with crystals. There's not a lot of money in them, but if you keep destroying them, then at some point you may get a lot of money.
The obvious way is to defeat opponents. They may have crystals or interesting items that you can sell and earn some extra cash.
Just explore the map thoroughly and destroy any opponent that stands in your way. By doing so you'll make a fortune quickly.