Nice light painting! Have you posted a simple tutorial for how you did this?
I haven't here, so here's the basics. Set the phone to manual and take some test shots of your background to balance the overall exposure between ISO and exposure time. The longer the exposure time, the less your ISO can be (which also gives you less noise). Needless to say, a tripod is a must, and black clothing I'd recommended.
A lot of this is trial and error getting the light balanced, so just play around. Using the LED's on a string, I just spun them in a circle. By setting the timer on the camera, you can get in place and get them spinning before the exposure starts. Otherwise you could get a leading trail like this while walking into place (from my G4).
I still like that one and call it my yarn ball, so feel free to experiment to see what you like. There is no right or wrong here.
For the ones you can see me in, you need to use rear curtain sync. This exposes the entire scene, then only fires the flash at the very end. That's why the LED's have the trail showing up but I look sharp. If I didn't use flash, I would look blurred and ghostly at best. For the V20, I recommend using the wide angle lens so you can get close enough for the flash to be effective. Too far away and it won't light you up.
For the orbs, use no flash. When spinning the LED's, you need to keep your hand centered over one spot on the ground. Using something like a leaf as a marker on the ground works well. Start the timer and get in place to start spinning. Then walk your body around the marker, keeping your hand centered over it. The speed of your body movements don't matter a ton, so long as you keep moving. If you stay in one spot too long, you'll start to show up like a ghost in the final image. Keep this up until the exposure finishes unless you want to add some trails leading to/from the orb. Side note, these are difficult to get looking like smooth spheres. Mine are rather sloppy.
For my sign off, the LED has a momentary switch so it's only ON when actively pressing on it unless I lock it like I do in the orbs. Then I simply press it while writing each letter in the air. Just remember you need to stand behind the LED and write mirrored/backwards so your body doesn't block the light. Practice your movements before trying the image. You have to move quick to prevent ghosting yourself. Using a bright light, a really low ISO, and a longer exposure helps here. This way you can write quickly, then get out of frame so it can expose the background by itself for the rest of the shot. This can help minimize ghosting if that's been a problem for you.