Before I joined my camera club I had no idea what a catch light was until a judge criticized one of my photos for not having one.
Here's an explanation.
Catch light - Wikipedia, the free encyclopedia
I also had a judge criticize a photo of a fish for not having a catch light. Then she said, "Well, maybe you can't really get that."
Getting them in fish is really hard.
There are some generally accepted *rules* of composition. I'm learning new ones all the time that have really helped me. One of them was aspect ratio that I just learned last month taking an uw photo workshop in Cozumel. The teacher gave a 2 hour class on composition. Once you have a general idea of what the accepted rules of composition are, then you can have a lot of fun breaking them!
And when you break them, and it works, that is sweet. You should see if you have a camera club near you. I learned so much from competitions, workshops and just hanging out with other photographers. There are also online forums where you can learn a lot. This is a pretty good one.
Steves-digicams.com Forums The most important thing, of course, is to HAVE FUN!!!
BTW, I really learned about blown out highlights the hard way. A judge was particularly brutal critiquing an image of mine during a competition (scored it a 5 which is a total insult score
) and I lost a night's sleep over it because I thought it was one of my best shots. I emailed it to another member of the club and she said to me "The first rule is, never lose sleep over a score." How right she was.
Good luck