This tutorial is for Adobe Photoshop:

Have you ever needed to add some water drops to an ice cold drink or something else maybe to give it that extra hint of realism?

Step 1: First you need to have a new document with a colored background, darker colors work better.


Step 2: Create a new layer. Using the lasso tool draw water drop shapes on the new layer.


Step 3: Go to menu item Select->Modify->Smooth. I used a setting of 5, but it really depends on the size and resolutions of your image. This image is 72dpi. If you are working with a high resolution image the number setting will need to be higher.


Step 4: Fill the shape with a color. I used white.


Step 5: This is where the settings can very quite a bit, so you will need to pay attention and use your best judgement.
Double click on the water drop layer so that the Layer Style dialog opens.

Settings:
Blending Options
Opacity 43%

Drop Shadow
Blend mode color should be similar to the background of the image.
Opacity 4%
Distance 3px
Spread 0%
Size 4px

Inner Shadow
Blend mode color should be similar to the background of the image.
Opacity 71%
Distance 7px
Choke 25%
Size 14px

Inner Glow
Blend mode color should be similar to the background of the image.
Source Edge
Choke 20%
Size 5px

Bevel and Emboss
Inner Bevel
Smooth
Depth 220%
Size 7px
Soften2px
Shading Altitude 70
Check the Contour box