Like what lolix said: katie > bashira > iris > bernice (add bashira and bernice to your core team NOW)

I would prefer if you skip silver archers if you are a premium user. Because you can just farm 200 DC on a thursday for the awesome spica.
200 DC = 10-15 SC if you rush for it (better to do once you get your core team up...you need roughly 1 CC-ed archer + healer thats all)

Alissa's 30CC is salvagable. Just DO NOT put Aff on her or Lvl her. She can be considered "AW fodder"

Your NO.1 priority is to get your core team to 30 then CC30. Start with bashira unless you got spica or nanaly. Archers are essential in all stages.

Save silver units. You'll need it for CC+AW.
When in doubt on what to level, always follow the colour code: Black first->Plat->Gold->Silver last
Especially true since you can spend to cost down your units.

Affection is most useful for units of higher rarity meaning blacks and plats benefit the most from it. Use it on them first if you deploy them frequently. I myself didn't max aff on katie till the 5th or 6th unit.