some tips?

[StrategicReef]

OK I am using my new D40X not really sure what I am doing..

what should I be messing with first? ISO? White balance? I am using the auto mode right now everything looks soo much better than my P&S. I understand somethings like shutter speed but havn't figured out the buttons in M mode.

Should I be using Raw format or Jpeg?
I have a tripod when should I be using it?

[swjim]

This site has some good general photography tips focused around shooting aquariums: http://www.ximinasphotography.com/lessons/

[gregr]

what should I be messing with first?

Your head First thing to mess with is learning what the different settings [iso, aperture, shutter speed and white balance] are and do.
Here's the basic rule in photography: for every change you make in one setting another setting is affected. It's all about compromise-- you have to compromise one setting to get another setting just right, and when you know what the best compromise is you have mastered the technical side of photography.
In a nutshell raising the iso allows you to use a faster shutter speed because it makes the sensor more sensitive to light. The upside is the faster shutter speeds- the downside is the higher the iso the grainier the picture.
Regarding white balance- basically it's something you need to worry about when the colors in your photo don't match reality. If your colors are coming out ok in auto mode then you can wait to learn about white balancing.
Raw vs. jpeg-- that choice mainly revolves around the color [wb] issue for beginners. Advanced photographers generally shoot RAW as a rule. The main reason to shoot in the RAW format is this: you can change the white balance after the photo is taken, on the computer. So if you shoot in the RAW format there are extra steps on the computer side- that's the compromise there. You need to convert that RAW file into a jpeg (or tiff or psd, etc) file to share it with other people. During that conversion process you have the ability to adjust the color temp. [wb] along with the other basic settings [exposure, contrast etc].
Use your tripod when your shutter speeds are slower than 1/focal length of the lens. That means that if you're using a 90mm lens your pictures will be sharper off the tripod when the shutter speeds are slower than 1/90. That is a basic rule of thumb- some people can get sharp results at much slower shutter speeds. If the subject is moving (like a tang for instance) you'll need a faster shutter speed to freeze the movement of the subject.
Hope this helps