Hello there Hoshi,

From my experience with Realflow, particles are best suited to gas/fire efffects and dust. To do a good looking fluid, you want to export to a poly mesh. Realflow still uses particles to calculate where the poly mesh will be, but you render a mesh in maya, as opposed to 100s of 1000s of particles. Which, if you think about it is the way that real liquid behaves - it's a solid unbroken surface whose movement is controlled by the interactions of the molecules that make it up with one another an objects in the world surrounding it.

Here's a link to the tute I used to get started, I realise it's for MAX, but it's really not all that important. It's the concepts and workflow that are the key to success here.
Realflow 'liquid into a Wineglass tute'

Hope this helps explain it all.
S.