Many neon gradients to add an interesting glow to your work!
I was playing around with neon lighting and had a fun time experimenting with colors. This is what came out, hopefully it can help you make some fun night time glowy effects. :)
My quick way to make neon signs:

1. Brightest layer
2. Secondary Color Layer
3. Glow eminating from the light
4. The Gradient
The thumbnail was made with 2 gradient layers, like so:
Original

Gradients, normal mode:







For most of the multicolor ones, I like using [color] or [overlay]. Each mode gives a different effect, feel free to experiement with other modes. :)


Here's how I added the gradients without losing his colors:

1. Lineart
2. A clipped layer at 64% opacity in [color] mode.
3. A grayscale version of the character, at 70% opacity, [normal] mode. This is affected by #2. Changing the opacity of this changes how much his colors appear over the gradient.
4. The gradient, which affects everything below it.
5. The original grayscale of the character at 100% opacity. This layer is affected by both the gradient layer (#4) and the duplicated layer (#3) + [color] layer (#2) above it.
Don't be afraid to adjust the gradient to your picture. Move the sliders around, add or remove colors, adjust it however you'd like. :D
Hope this helps you guys out and hope you all have a good day, thanks for taking a look! Feel free to @ me on twitter @saturns_day if you use them. :o