What's the more appropriate way to introduce a "flashback" in a graphic novel, in terms of color, line strokes and panel shape?
i'm in the process of making a graphic novel together with a scriptwriter. We're both at our first attempt in making a graphic novel although we are not new in drawing (me) and scripting (him).
This is the first time that i have to deal with a "flashback" situation without explicitly stating FLASHBACK (or whatever kind of sentence may work) on the panel. Just drawings, no captions or baloons.
I thought of a change of the mood (light color) and play with the resemblance of the charachter in the past, but i don't know if it's enough.
There is also the possibility (i've not read the whole script yet) that i would have to draw flashbacks occurring into another flashback, someone would say "flashbackception"?
How should i handle this?
Any advice, experience or useful links on the topic are appreciated.
EDIT: What i've read so far
Using black as the outer colour of the panels seems to work in my experience.