No Man's Sky offers a vast array of options for acquiring cash, and here you'll find the best methods for acquiring funds to fuel your adventures.
IDENTIFY AND NAME
The first way to create an influx of cash in No Man's Sky is to identify the things you discover and upload them to the database. You do this by opening your scanner and viewing animals or plants, by finding outposts and locations and using the marker there as a save point, or by simply landing on a planet or entering a new star system. Once you have completed one of these, press the start button and hover over the item you wish to upload. You can either direct upload with Square or name and upload with Triangle. Naming doesn't net you any extra cash, but it does make you feel one step closer to filling the shoes of Picard.
MINE WHERE THE RICHES REST
Upon landing on a planet, you will be notified as to the overall abundance of materials. When planets are resource rich, they are simply begging to be mined. For instance, mining a planet that has an abundance of Copper can be a great way to create an influx of cash, and finding a planet rich in a great resource like Gold, Copper, or Iridium, will allow you the opportunity to make financial gains fast.
IT BURSTS FROM THE CHEST
When exploring your planets, keep scanning the environment around you as you search for materials. When you see a gray chest icon, move towards it. These can hold a number of possibilities, usually granting highly valuable elements to sell or use in upgrades.
EXPLOIT THE SYSTEM
When you reach a star system, first travel to the space station and take a look at the Galactic Market. Here you'll be able to see which items sell for a premium, some of which are craftable. My personal exploit was Electron Vapor, which was easy to craft and fairly quick. Determine which materials would sell for the highest amount, and then explore the planets searching for them. Load up on these materials (or crafted items, most likely) and return to the space station to sell them off. Rinse and repeat.
An extremely rare and valuable resource, if you happen upon a planet with these, collect as many as you possibly can. Be careful though, as the moment you take the cube, level 3 sentinels will begin attacking you. Try to land your ship in the middle of a couple of these, snag them and fly to another location with them. Each one can be worth upwards of 40,000, and is a great way to start your path towards financial exuberance.