I have a cheap $50 Kodak...
First, you need to know your camera. You need to know what it does, which will take a while of sitting and tinkering with it.
What I do is put my camera on the largest MP setting, this controls how big of a picture you take. The bigger the picture, the more details.
Then I step back a bit from the tank, and take photos at an angle to avoid the flash on the glass. Take about 50 photos.
Then I put them on my computer. I use a program like Picasa from Google, it's free. I usually crop only with this program, but you can add some color and sharpen it as well. And that's how I get my pictures :)
Not bad for the cheapest camera walmart has?