... And how do you increase dilithium so you can convert it for C-Store points?
Missions. For example, "Assisting the Deferi" missions from Ambassador Surah can net you 3600 dilithium. Commander Makza has missions to Ker'rat, which can net you 1400 dilithium each completed mission (3 Ker'rat instances). You can stack it up doing those. There are lots more. You can also get dilithium from your DOFF missions.