Rendering and shading fluids is definitely tricky, but if course it very much depends on how you computed them in the first place.
If you have a eulerian grid which you used to compute motion by diffusing and advecting velocities / temperatures / densities / colours, you can pretty easily ray trace through the volume and get some decent results, depending on the resolution of your grid.
If you went down the sph / mass particles way, I find it trickier. Depending on what kind of fluid you are trying to render, you could render multiple times, to get surface depth and thickness, and then composite together.
Or you could try sorting them and alpha blending them. Of you could try bucketing them into screen tiles/cluters and evaluating each block to reconstruct your surface. Marching cubes could be an option?
You mean that different fluids, like difference between ocean and a cup of water, will be simulated in different methods( I think maybe it's just a something detail in equation's item, is that right ?) ? I'm stopped at surface-reconstruction, that's very hard to me. I try to read a lot of opensource and thesis, then I can do next.