I recently took up a photo challenge that had three guidelines: 1) the subject was to be flowers, 2) you were to use a macro lens, and 3) you were to illuminate the flowers only with a flashlight (the room being otherwise dark). I began with the idea to illuminate the flowers from behind, hoping that the petals would be thin enough to allow some light to pass through and thereby make the flowers glow. That approach worked well for the Iris, the Rose, and the Columbine.
Other flowers were simply too thick with petals and transmitted no light from behind, so I shined the flashlight directly on the flowers, as with the Mums.
For other flowers I realized I could get the glow effect to a degree, but the lighting could be improved if they were also illuminated from in front or from the side. Rather than try and juggle two flashlights, I used in-camera multiple exposures. I would take from one to four exposures from behind and a single exposure from in front; these were combined in camera to produce a single picture. As you can imagine, the lighting was not repeatable exactly, so I took many tries before getting a picture with nicely balanced lighting. I used that approach for the Anemone and the Weigela.
I lit the Alstromeria from each side and from above (again using in-camera multiple exposures). I took several such pictures and then picked two where the shadows were slightly different; I then blended those two photos in the computer. The total effect thus uses exposures combined in camera and in the computer.
The Woody Peonies were my favorite: the flowers were complex and extravagantly colored, and the petals transmitted just enough light to glow with the colors of the flower. I again used in-camera multiple-exposure to get illumination from in front and behind. For some of the images, as with the yellow peony in the vase, I used two or three separate such multiple-exposure pictures and subsequently blended them in the computer.