I would like to know how you play and plan your playthroughs in the Void.
Do you plan the entire thing from the very start, see what situation the new cycle brings
you and adjust accordingly or do you have a completely different tactic?

Personally I don't plan far ahead. I prefer to see how well I can play the cards I get during the
game.

I find that it is basically impossible to plan further ahead than the end of the current cycle in most situations.

Yes but you can plan wich sister to visit when and what colour you plant.
I just plant what I have and visit the sisters according to the colour I have most of.

Ah. I plant the color that I need most, and try to keep 100 drops of violet, silver, crimson, azure, emerald, and gold in my memory at all times, so that I'm flexible to the situation.
In fact, the only color I don't hold on tightly to is amber, which I try to have at least 100 drops of in my heart at all times.

I use color indiscriminately, then save right before the cycle ends and reload until the next cycle brings me the colors I want.

Just kidding. I only did that once on cycle 5 or 6. I was trying to unlock Uta's second hard for the Warden's quest but the game absolutely refused to give me silver, emerald or gold. I just barely managed to scrape together enough color to please her.

The only thing I really plan in advance of the current cycle is which Sister I plan to ascend. Other than that I try prioritize sisters that will open Gardens, and keep lots of Azure planted because I'm kinda addicted to moving as fast as possible.