Step 5 For the jellyfish, I chose a basic brush with soft edges and created a new layer with an Outer Glow effect (Layer > Layer Style > Outer Glow). Using a bright colour (#ffffbe), I set the Opacity to 64% screen and painted them with quite a large-sized brush.
I used the same tool for adding some water bubbles all around the place.
Step 6 I added more water bubbles here, using a brush with hardness set to 100%. I tapped here and there using different opacities and various angles and roundness, all of which can be changed in the Brush panel.
I also added some more light in the centre, both behind and in front of the two main figures.
Step 7 To bring the ghostly collective to life, I placed all elements on either side of the main image and performed a group merge (Layer > Merge Group) of these layers. I made a new layer and copied the outer glow effects.
To do this, I right-clicked on a layer and chose Copy Layer Style, then right-clicked on a newly added layer and chose Paste Layer Style. I used a small sized brush to paint ghosting on the edges – so it looks like the figures are crackling with electricity.