In my previous lab we had good results mixing 400 μL of yeast cells (OD=1) with 20 μL of DMSO and incubating for 5 min,  then adding 500 μL of PBS pH 7,0 and 100 μL of Nile Red (0,1mg/mL) and then incubating for 10 min. We used it to measure fluorescence in a VICTOR X3 plate reader.

Fábio did you test it for microscopy? I mean, staining the cell using that protocol and then analyse them using fluorescence microscopy?

We did not apply that protocol to microscopy, but I believe it would work with a little bit of optimization (cell number, incubation times..)