Play 1-3 or 2-1 until you're bored. Don't kill the raid boss if it spawns as it can block the secret garden. That's pretty much the trick.
As for who to level, just pick whoever you like. The power between silvers isn't that much.
JP wiki mentions Yulan, Hinoki and Cyani in particular are outliers, but you only have one of those.. who shares the same type as Orchid.
Just do whatever imo.

Ok, if you're actually using that team line up as is, that's part of it. Yeah, use the "total power high-low" for the my-set one, but don't actually USE that set to do the levels, you just do it so that your helper squad is strong to aid OTHERS. Use the other tabs to make ones for yourself to use. Main thing is balance the power out on your teams. Your top team in your current setup isn't gonna have issues, but the rest likely are, so you want to balance it out so that while every team my get a bit beaten up, they still are capable of killing the enemies and at the very least making it to the boss (some likely WILL die on the boss, but with others behind them, its not the end of the world)

you actually have better raritys than me lol. I only have 1 5* and 6 4* now. after 2 10+1 rolls.
what you probably need is to level your core team up more. to 50evo30 with 100% affection. which you will get there eventually. then you'll be good. and like tenhou said, farming 2-1 is good.
also, dailies is not actually efficient for manyu. because no exp. when early on, the exp gives you levels = more stamina = more runs = more manyu.

regarding what moople said about team setup:
my farming team: (for reference)

->Open Spoiler<-

vs my high power team:

->Open Spoiler<-

Good grief! How did that not kill off your teams when going for 3*? I couldn't get the full 3* past area 5 until I balanced out my teams a little, I kept having at least 3 of the groups die off before getting anywhere near the boss. I mean, I got the stage down, but I never could manage to get every pest.

Thanks for the advice everyone! So aim for 2-1 for now until everyone is at lv. 30+. Got it. Yeah, I should've had higher level units since I did get a week head start living in Canada and all, but exams kinda took some time off. Btw, forgot to tell you guys that I'm lv. 27 right now. Planning on attempting Orchid's second quest mission once I reach lv. 30.

@MoopleFoople - Not sure if you were referring to me or sora on your second post, but if it was for me, then I guess RNG and a good helper carried me past the 7th stage lolz. That and I probably had some good ATK/DEF equipment for my teams.

No point in doing the character quests before you have evolved the girls and gotten a better team. The final one requires the girl to be evolved and is the only one that gives anything worthwhile.

Got one more question before I set off to farm the 2-1 map: When doing farming in the daily missions, is it better to do the 50 stam map or the 80 stam map?

1) people answered...
2) I've heard having teams of all lvl 20s is enough but we wont know till its actually out.
3) I'd say focus on your 4/5*s now since you've gotten a decent base team already. I'd say get them to lvl 30 each if not higher (more for Orchid). You should probably start looking towards evolving some of them.

Another important thing is focusing on affection. Its crazy powerful for 4/5*s so if you haven't already I'd say run ?-4 of the event mission until you can 100% most of your 4*s. Since gifts are pretty hard to come by outside of event missions and the gift special quest is horrible outside of the 2 flower gems.