It is not good to focus the camera directly at the sun for a long period of time either for your eyes or the camera sensor. What I try to do is
1. Prefocus, so for good depth of field, about one-third of the distance between my position and the horizon. Switching to manual focus can help.
2. If you take a meter reading directly into the sun, your image will come out dark because the sun is so bright. Try metering off to the left or right of the sun, so the brightest part is only at the edge of the frame. See what the metering tells you for f-stop and shutter speed.
3. If your camera has auto-exposure lock, A-E L, push that button, reframe the sunset and take your image. Alternatively, after you take the meter reading off to the side of the sun, switch to manual and set the f-stop and shutter speed manually, and shoot your image.
4. From this starting point, you can adjust f-stops to bracket the image as desired.

Good luck with future sunset shots.