No pool time??? I am hoping that the environment is rather benign then, great viz, no current, shallow as in < 30 ft. I grew up a water baby, was naturally very comfortable in the water and still appreciated my pool time with the equipment in class.
I have been on a dive with a pack of discover scuba divers who had pool time, in clear warm water, 40 ft and based on what I saw (I was a newly certified diver hanging around them) I would not recommend people going this route on vacation. OTOH I know some divers who had no problems and became totally hooked.
If you are not already naturally comfortable in the water, don't recommend it at all.
The most important thing is your comfort at all points. In addition to all the book materials on how to dive safely, I recommend the following:
If you check out your gear and make sure it does everything it is supposed to do, make sure you know how to work it, inflate, dump and breathe off the both the reg and octo before you even walk away with the equipment.
stick close to the instructor
steer clear of wackos, if you are able to ascertain such a thing in your brief pre dive encounter with fellow DSDers
Before you even descend, breath for a while on the surface if possible to just get used to the sensation of breathing through your mouth instead of nose, until you feel comfortable.
Clear sinuses often, like every few feet, I think one of the more common mistakes of newbie diver is that they don't.
You will have no clue on buoyancy and they will likely overweight you. Stay on the line to better control your decent (will save your ears) and ascent.
that's all I can think of for now