Hi! Welcome to Splinterlands!
Not sure if you're already doing this, but one tip that we can give you to increase the chance of your cards being rented is to list the cards at a lower price than the other listings. If you're planning to do that, this can be easily done via the Renting Out feature in PeakMonsters :)
Of course the main drawback of this is that you will be getting less DEC/day.
Sending here a how-to post link written by one of our users: https://peakd.com/splintertalk/@pogier/passive-income-through-renting-with-peakmonsters-its-super-convenient
Thank you. I appreciate the information.