This example is about a water drop effect on the leaf, you need not worry about a water effect on the any place because I have made this example that will help you surely to make it.
Open A File: First you have to open a leap picture to show a water drop effect on the leap as I have this image.
Selection: Choose Elliptical Marquee Tool (M key) and make a selection like a circle, copy of the selection and take a new layer then past it at same place.
Inner Shadow: Go to Layer Menu > Layer Style > Inner Shadow and adjustment the settings.
Drop Shadow: Go to Layer Menu > Layer Style > Drop Shadow and make adjustment.
The image should be similar as given below.
Lens Flare: Go to Filter Menu > Render > Lens Flare and make adjustment to give shine effect.
Shear: Go to Filter Menu > Distort > Shear and make setting to change the shape.
Recommend the tutorial