Can I ask for a more specific advice? My current goal is to increase my SED to manage to get in the 501 ~ 1000 rank range so I can get the limited SR card. I saw the contents of this topic too late (via google, when I saw it through the forum for the first time I assumed it's just the first post) and now I'm at the boss of 4-3 and holding at least until I get the SR card.

I have 24/26N, 14/20R, and 6/14SR of the gacha cards, facebook's Lilith Lil, and Kurito's limited N card.
In total I have 25N, 17R, and 10SR cards, my total SED is 60,083 at lvl 20.
Currently on 3362nd place with 94,751 EP and 41 eliminations.

Here is what I currently do:
Search for the Elite Guard and attack her, spend the rest of the stamina on 4-3 until the guard is defeated, since it gives more exp and pero.
Solo the guard if possible (so far it's always been possible unless we get a power outage or something).
Upon defeat of the guard I let the stamina recharge until the focus is full so I can look for her again.
I spend all the pero on 6x Gacha Tickets, which I proceed to use normally, since there are still gacha cards I don't have.
I complete the pie trowing daily mission and the first flirting mission with any gacha I've obtained, then start the triple chance mission for the rest of the day.
When leveling cards I pick the ones wih biggest max SED first.

Is there anything that can be improved? The person currently at 516th place has 130,906 total SED, so I think it's possible to get in the low end of the range if I get mostly 3x EP from battles.