Topsoil or potting soil better for new planting?

Yellow is probably your favorite color?
That would be a bit too much yellow for me. Maybe some red or blue for a change?

Great, did you notice spontaneously that they all bloom yellow or did you research?
Yes, it is a lot of yellow; I want to see what effect it creates. The color blue seems too "artificial" to me in the garden, with red I am unsure, maybe a bit too "aggressive". Possibly I will add some pink to the yellow, we'll see.
Currently, purple-colored plants are heavily promoted, but for our region that is also too artificial for me.
With my assessments, I do not want to offend anyone, everyone sees a color differently and colors also affect each person differently.

I think there are so many colors that can also complement yellow. In The English Garden there was once a report on Gordon Castle with planting examples. It doesn't necessarily fit your planting list, but I'm concerned with colors that go well with yellow. There is a bed called Golden Peat. There is the dahlia Cafe au lait or sunflower black magic. The combination ranges from cream white, through orange to black-red. Dandelions come by themselves. Be aware that the neighbors complain. That stuff grows everywhere.

I think there are so many colors that can also lighten up yellow.
In The English Garden, there was once a report on Gordon Castle with planting examples. It doesn't necessarily fit your planting list, but it's about colors that go well with yellow. There is a bed called Golden Peat.
There is the dahlia Cafe au Lait or sunflower Black Magic. The combination ranges from cream white, through orange to black-red.

Dandelions come on their own. Be aware that the neighbors complain. That stuff grows everywhere.

Thanks for the suggestions, I will research them right away.

Regarding dandelions, I thought if I cut off the heads when they turn into blowballs, they won’t spread to the neighbors?

Thanks for the suggestions, I will research that right away.

Regarding dandelions, I thought if I cut off the heads when they become seed heads, they won't spread to the neighbors?

Theoretically, practically it rains before you cut them, or you are away for a few days…
Do it anyway;).

Theoretically yes, practically you can hardly keep up. But they propagate on their own. I had tons this year.

You wanted to divide your garden into different areas, right?

I knew it with two of them (bzw war ja auch der deutsche Name einma "gelb") so I researched it. I find concentrated clusters of one color rather artificial; another color (no matter which) can only loosen that up and make it look more natural. But yes, that is just personal taste.