hopeful diver:
Have practised skills and don't feel quite so bad about them... however when I went on what was to be my first open water dive in the sea I could see wonderful fish below me but just couldn't summon up the courage to get down there.... as a result I got out of the water and quit for the day. I really don't want to give up - but just feel like I have reached a big stumbling block. It seems a bit like the 'fun' is actually 'torture' at the moment...
Think back to your dive. Why are you having problems? If its a "Oh no, now i'm diving 'for real' or a 'the stuff counts now' "thing, then realize if you can do it in a pool, you can do it in the open water. If you're afraid that your instructor is grading you more closely now ,don't worry about it, you'll be fine.
If, on the other hand it is something else, like the thought of going deeper than you can in a pool genuinely scares you, you might need to have a chat with your dive instructor.
You can, and have, been told there is no reason to fear
1>equipment failure
2>marine life
3>DCS/DCI
4>AGE
5>Being swept away
6>etc
But if you do anyway and can't get over those, that can be a BIG problem. Realize, if you are able, that the above concerns are very very very unlikely to be a problem if you are trained and follow that training. Don't rush things. Get geared up. Take a few deep breaths to calm yourself down, and then splash.
But if there is some reason you just can't do it (and its too early to tell if thats the case yet, you could have just had a bad day) its ok. Most here can relate to being nervous before a dive (That happens on some dives after your 100th dive).
Talk with your instructor and relax. Remember this is for FUN, not torture