Buy Steem when the prices are low
If you check my wallet you will notice that I have no SBD but I have a few Steem.
The reason is that what I do to earn a little money is I buy Steem on the Steemit's internal market when the prices are low and then sell them when the prices go up.
I have not made a lot of money with this method but I do say that it works and you too try this.