"..." talking
'...' thoughts
I'll add more to this if or when a flash back scene comes up, but they will most likely either say flash back before hand or if possible will just be italic all the way through. (hopefully the latter situation is possible)
Also if there are more than one set of "..." in a paragraph then it is most likely going to be the same person continuing to speak or think in the other case. I'll usually start a new paragraph if someone new is speaking and give signs to who is speaking before or after the "...".
Hope you all enjoy the story!