If your window has no casing but a blind, mini-blind curtain rod brackets are also a good alternative to fixed brackets. On a scale of 1 to 10, I'd give these options 9 or 10.

Screw in the brackets. Using screws and a drill or screwdriver, install the rod brackets. You can check that the brackets are level by mounting the rod without the curtains.

All you’ll need is a double curtain rod, a drill, a tape measure, and a pencil (and your plants, obviously). ... Finally, use your driver bit to screw in your brackets.