Ok, so today was my first serious open water swim (practice, of course) and after doing it, which I loved, I have the following conclusions/tips for other newbies like me:
-WEAR SUNSCREEN... I am damn serious, wear water-proof sunscreen and don't do it any time near noon. I feel like my skin is about to fall off.
-RELAX while swimming: face it, no matter how strong your shoulders are, you're not stronger than the tide of the ocean, so just relax and don't fight it.
-DON'T PANIC (bonus points if anyone tells me on the back of which book is this printed on) if you run into anything, chances are it's not killer-fishie, so just calm down, take it off you (it's probably a plastic bag or some algae) swim slow for a few seconds (don't start trying to out-swim it, you'll get tired) and don't panic. You'll be back in pace in NO TIME.
-Stay near the shore: it's your first time, don't wanna do anything stupid.
-Get a spotter or swimming-buddy: it's more fun
-Figure a pace for your breathing: conciously count every how many strokes do you want to breathe, and every how many breathign cycles do you want to look for your objective for direction.

This might sound silly for the great majority of you, but it's just what I learned from my first experience with open-water swimming and I thought this could help somebody.

Nayo
PS: I suck at swimming, so I ain't giving any tips on techinique or anything.