So as a begineer, when I first started playing Splinterlands I wanted to get my collection power up as soon as possible. And I decided to do this by purchasing as many gold cards as possible. Big mistake. This is an expensive way to go about it. So I decided to change up which gold cards I buy.
I developed a strategy for winning battles and found out which cards I used the most (in this case it was the venari wavesmith). So then I bought the gold venari wavesmith. This allowed me to win a +10% bonus of DEC everytime I won a game. On top of that, I wait until the day before the season ends and I rent this card out. Normally, the rental rates for gold cards are very high the day before the season ends. Last season I was able to rent this card out for 90 DEC a day. Between the DEC win bonus and the DEC I would get from the rental payment, this gold card will eventually pay for itself in a couple months!