Step 4. Make these duplicates real (Ctrl-Shift-A). This turns each drop into an object. You can now delete any overlapping drops or weirdly angled ones and tidy up where they fall.
Step 5. I duplicate some drops in little vertical trails getting smaller as they go upwards, something I noticed in my references. You can do this for multiple drops at once using the select random operator to select say, 10% of all drops. Then duplicate and scale down (to individual object origins). Make sure you only duplicate drops on vertical surfaces though or you’ll get drops floating in space!
Step 6. Finally I sculpt one or two longer, trailing drips going down, these catch some nice highlights and make the drips look more varied. To make these I just projected a thin strip of poly’s onto the can mesh and then extruded them out to make a manifold mesh, and did a bit of dynamic topology sculpting.
Step 7. Finally (optional depending on the surface you’re adding drops to) I add another particle system for some really tiny drops. This time they’re so small it isn’t really necessary to make them real and tweak by hand.
The material for the drops is really simple. Just a glass shader, IOR 1.33 (water). It’s worth noting that the drops don’t have any back face though - they just clip through into the can.