Abilities » Make Do
Can I use Cinccino's "Make Do" Ability if there are no cards in my deck, just to discard a card?
No, you can't use Make Do if there aren't any cards left in your deck.
Source: Sword & Shield FAQ (2020-01-24), TPCi Rules Team (2020-02-06)
Abilities » Make Do
Can I use Cinccino's "Make Do" Ability to discard a card, then do other game actions such as play a Cynthia, and then finally draw the two cards later in my turn?
That's not how it works. You have to perform all of the actions of the Ability before moving on to other game actions.
Source: Sword & Shield FAQ (2020-01-24), TPCi Rules Team (2020-02-06)
Abilities » Make Do
For Cinccino's "Make Do" Ability, can I use it when I'm discarding a card as part of some action or effect?
No. Discarding a card from your hand is part of the cost of using the Ability. You can't use a discard done from some other effect or game action.
Source: Sword & Shield FAQ (2020-01-24), TPCi Rules Team (2020-02-06)