Just created this very quickly about 5 mins (not rendered of course, just in the viewport), should give you some pointers.
1. Create a 3D fluid container with a sphere volume axis.
2. Set density emission to 4, emission turbulance to about 5 with a detail of about 0.2.
3. Set the res to about 30 - 40 with auto resize (speeds up sim times)
4. Set damp to 0.01 (essential for any sim) and high detail solve to all grids.
5. Contents details - Density set dissapation to 0.1.
6. Velocity set swirl to about 7 to get eddy's.
7. Adjust the opacity ramp to 0 to start then a ramp up at about 0.061.
8. Add a wind field to move it slightly in one direction.
As David said fluids are difficult to do correctly as they are a balance of a lot of settings and take a long time to learn.
"No pressure, no diamonds" Thomas Carlyle