I've tried growing these but can't Tell me what I can do next season so I can have them alongside the bluebonnets.

I see patches of them along the highway...

Well Betsy, you're doing better than I. I can't get the bluebonnets to grow. I tried the Indian paintbrush & got nada. So that's 2 strikes for me.

Indian Paintbrush is very hard to grow, it grows in association with certain grasses and it doesn't do well in regular garden situations.
I love it too, and tried to grow it some time ago, but it died out, I figure I will just enjoy it on the prairie.

Indian Paintbrush grows fine in my front pasture with the bluebonnets, prairie verbena, and native grasses. In a fertilized flower bed composed of potting soil, it probably wouldn't be very happy. The roots of paint brushes need to tap into roots of other plants in order steal their nutrients; hence a "weedy environment" is crucial. Guess you could call it a Vampire Plant! My natural soil has a lot of limestone rocks which add to the alkalinity so that probably helps too.
You are in a good zone for them so you should have good luck as long as you don't pamper them. Hope this helps. Don't give up!

Oops - sorry about that sideways photo.

Ooooh, those bluebonnets and indian paints are just lovely together, @Grammachar.
The seeds of Indian p. were from LBJ... gotta find more seeds. You wouldn't be collecting some seeds?

I sowed them in raised bed that have red porterweed, verbena, red shrimp plant, and others but no germination; hoping they would latch onto the other plants.