The ideal is to have a multitude of colors that will create variations. If your tray contains the colors or patterns that suit you (you have to test it!), it is not necessary to place the entire leaf underwater, it may only be halfway there; everything will depend on what you decide to do based on what you see in your photographic viewfinder. 

Any modification of a few centimeters - even millimeters - allows to have a different light.  It is the flash that will be reflected in the colored paper that will face it that sets the tone, or rather, the lights and shades. If you have several flashes, at least one of them must be placed directly in front of the subject (papers in the background, falling water drop...).

The use of aluminium type papers gives very surprising results due to the wonderful bokehs that emerge from them.

Sometimes I work with clothes whose pattern or colors interest me, but it's more complicated because the fabrics swell underwater; or with dishes, and when they're white, you can imagine almost anything.

Like placing small stones, colored beads in a white dish, or as described in the lower left corner of the illustration), a few small glass pebbles in pastel tones that can be found in aquarium shops. Then I added pieces of plastic bags, pink and blue, to match the small glass pebbles. Again, changing the layout of the glass rollers and/or colored plastic ends will change the final result.

The possibilities are endless!

There is no limit to imagination and experimentation. Anything can work more or less well. Imagine, test, create...

I hope I have been able to enlighten and/or help those of you who are wondering about the technique by seeing some of these pictures; most of the photographs have the following EXIFs:

Apertures from f/2.8 to f/4.5 

Shutter speeds from 1/60 to 1/200