You can also win SPS as a currency. That you can exchange for DEC, which then is used to buy more assets (cards and so on). The higher your league and the more owned cards you play, the more rewards you get :-) Also, joining a guild will provide you with some boni.
Check out the @splinterlands community challenges - there are a lot of helpful guides there :-)
Have fun!
Any guilds you recommend? Or is it better to start one and build organically?
Building takes a long time. Look for open guilds here:
https://splinterlands.com/guilds
Most guilds will need you to contribute in both DEC (called Guild Points/GP) and guild battles (called brawls). Best start out in a guild that is quite low, learn how everything works, and then you can decide if you want to apply in a bigger guild.
You can also look around and see if you can find small guilds that are attached to bigger ones. I think Fallen Angels have a few branches, same for the Pizza guilds - there you can find a lot of support as well.
Thank you very much for all the info!
You're most welcome! I hope it'll help you enjoy the game :-)