I think you're on the right path. I agree with everyone on the tripod. I bought a cheap $35 one about 5 years ago and still use it today. A better tripod would most certainly help, but the difference between a $35 tripod and an expensive one is smaller than no tripod at all and a $35 one.
The other thing to consider is the amount of post processing you do on your photos. When I take pictures of my tank, most of the time they don't look so good coming right out of the camera. I shoot mainly in a greenhouse with no artificial light, and there is a lot of haze and light scattering going on. I need to do a good amount of post processing to make things look right.