Dweste, if you do Psychological First Aid (PFA) the way the Red Cross teaches/recommends it, I think you're good to go. I just don't like the "debriefing" components some people seem to use.

The World Health Organization (I think in recent years... at least after 2007) looked at PFA across the world. They DO seem to endorse: "basic, non‐intrusive pragmatic care with a focus on: listening but not forcing talk; assessing needs and ensuring that basic needs are met; encouraging but not forcing company from significant others; and protecting from further harm." PFA is very different from psychological debriefing in that it does not necessarily involve a discussion of the event that caused the distress..."

Psychological First Aid is designed to reduce the initial distress caused by traumatic events, and to foster short- and long-term adaptive functioning. I really can't find compelling evidence that it does the later (promotes long-term adaptive functioning). But that's a hard case to make in any event because of "base rate" problems: 70% of survivors do not suffer any such consequences. Of the 30% that may, we still aren't very adept at identifying the factors that explain who will or won't have consequences.

Here's a guide to PFA:

http://www.vdh.state.va.us/EPR/pdf/PFA9-6-05Final.pdf