Photoshop Beginners Water Droplet Tutorial

Video:

Step 1: 
       Right-click on the Leaf Image at the bottom of this Tutorial and save it to your desktop then open it up in Photoshop.

Step 2:
    Double-click on the Background Layer in the Layers Panel and change it to Layer 0

 Step 3:
     Click on the 'Create a New Layer' icon to open a New Layer above your Leaf.

 Step 4:
    Select your Brush Tool and with a hard edge Brush paint some spots of various sizes across your New Layer, using Black as your colour.

  Step 5:

     Click on the 'Add a Layer Style' icon.

       Apply the following ↓↓↓

     You may carry on painting water droplets onto this layer with your Brush until you are satisfied with the result.

Resources 
http://www.wallpapers247.com/wallpaper/Green-Leaf-01/