I have been doing this for a number of years, one of the reason is I use them for backgrounds, lately for artistic pictures, some may like it and some don't, I happen to like it and find it rewarding and very fun.
I also find it addictive. If you would like to learn more you can watch this Video that B&H put out here https://www.youtube.com/watch?v=5HiZ6zSStBo&t=3078s

The video is somewhat long and to make a short list that I have learned,

1. A tripod really helps, and lock down the horizontal control to where you only have up and down movement, having said that a tripod is not a must and I just hand hold a lot of times, my tripod is not the best for this because it is a ball head and wonders around anyway.

2. Shutter speed, I start around 1/25 sec in manual mode and work from there, normally ISO 100 and use your aperture to adjust your exposure, some where around f/16 is a good start.

3. Focus, even though is called Pleasing Blurs, you do want to get really good focus on your subject. I find manual focus works really well.

4. Lens, just about any lens will work, this week I shot some with a 55mm, I find my 90mm macro works best but have used up to a 400mm

5. Sweep, you can sweep up or down to make it blur, back and forth what ever you want to do, I find it easier to sweep upward with a heavy big lens, you don't want a heavy lens to bang your tripod on the way down, you may sweep fast, slow, or even just the flick of your wrist.

6. Shoot many pictures of your subject, although it might look good in the camera, it might not be the case when you get them downloaded, once you download them you will find one that will really stand out from the rest and say that's it, and it will put a smile on your face. It's not unusual for me to shoot 10 or 12 shots per subject, some times it's all about timing, to hit that shutter button just at the right time while you sweep.

Some of these pictures were edit to the extreme with On1 Raw and Topaz Adjust and other software, some are just right out of the camera.
If you would like you may use any of these for background pictures or overlays, the only thing I ask if you do is show it to me, just because I want to see it

Please use the down loads and have a great day!!!