Less=more is definitely a good theory!
I stick by what I enjoyed in NL, which was mixing/matching colors AND breeds.
I really don't like having all one breed in an area. Same color is okay, but mixing colors is definitely nice too.

I only just started playing around with laying out flowers, since I started getting enough "stock". I'm still missing some of the flowers I want to use though.
I really love green mums. The color is just so neutral and pretty.
I also love white anything - again, the color being neutral makes it very useful.
Generically, I am a big fan of the Hyacinth! I have very few since it's not my native or sister flower, but I'm working on getting more. I also love mums and cosmos (cosmos are just SO CUTE and mums look like weeds and I'm All About That Look).
Windflowers and pansies are probably my least favorite? Idk the windflowers just look kind of off to me (blue is great though) and the pansies are just really dark in general.
I started with tulips, which I'm also not a huge fan of. I think they look good in moderation.
Anywhooooo, I saw this reference posted here on TBT before, this Reddit user is SUPER inspiring:
Here's their posts with all the layouts they've put up.