For EC:
Do the Daily travel through the space
Select the german foundry Valas lowlevel farming quest (pure kill and if one ship detonates and if its near the spawn spot it damage the new ship)
Allways sell Blue/Purp items on exchange if item price on exchange > 1/3 of item price
(in the delve of item)

For Dilithium:
Do Reputation Pve Maps and transform all the reputation marks to dilithium
If price is dropping on dilithium Zen exchange and you allready got a lot of zen sell your zen and buy if price is incrasing again since:
8000 Zen sold for 254 each = 2032000 dilithium
then bought 8000 Zen for 237 each = 1896000 means you won 136000 free dilithium

For Fleet credits:
Create an own guild stay in it with one toon and join with the rest a big fleet
couse much fleets got that much members you often dont have time to spend before its filled. then do the fleet mark maps and donate since fleet marks give most credits so you can invite one of the other toons to your fleet donate and move back to buy stuff and play again with your fleet

On your Char sheet you have even Abilities be sure you set em since they not autostat couse a few guys running around with non set abilities and wonder why they deal less damage with same spec and gear and some.

For the Ec you can buy stuff like:
Keys to open lockboxes
craft nats /upgrade mats (sometimes cheaper then buy just the item you need)

Dilithium:
Ships
Gear (reputation/fleet you just need have the required reputation marks /elite marks