At least try to cast actors that are close to 18 for once and not people close to 40 in these horror films. Another stupid American stereotypical portrait of South American people also don't help. Only some attractive girls getting slashed open may be interesting for uncritical gore-hounds to see.
In all endeavors where there are a large quantity of unknown elements, there needs to be at least one person who keeps muttering softly, "We're going to die". I was that person in my group of friends. It doesn't matter that we didn't die. It meant that I was always on guard. One time I noticed a guy was following me, and I went to the other side of the street. So did he. So I went into a store and waited him out.
My biggest problem with Turistas wasn't the acting or the overall idea of the film, it more revolved around the fact that nothing really happens. Perhaps if the entire first act had been shortened, not playing on the whole partying sequence for so long, maybe something would've been able to develop. As much as I like stories where characters are placed under extreme circumstances, this one didn't quite do it for me.