What is the best way to paint concrete floor?

Here is an interesting product made specifically for garage floors. I know you didn't say if this was for a garage or not guess took a chance with the info. Hope it helps!

https://www.rustbullet.com/advantage/long-lasting-floor-paint

If it’s never been painted before, then I would use a concrete dye/stain.

Mute never going to peel, it permeates the concrete and comes in any color you want.

It can be sponged, sprayed, rolled, stippled- into any textures or patterns you can imagine. I’d get two colors, personally.

The concrete will need to be cleaned first.

https://www.hometalk.com/search/posts?filter=paint%20concrete%20floor

We painted our concrete steps after refinishing them! See the whole tutorial here: https://www.aratariathome.com/blog/how-to-update-concrete-steps

We bought a paint at Home Depot that was made for concrete floors. It's been on the basement floor for years.