Recreating Condensation on Glass

We will start with the image we want to add condensation to. In this demonstration, we will be using the following wine glass:

The first thing we want to do is to make a selection of the main area of the glass and duplicate it. To do this, we will make an initial selection like so:

Then we want to right-click the selection and choose Make Work Path. Tolerance of 2.0 is fine. Now choose the Convert Point Tool () and adjust the path like so:

Next, choose the Convert Point Tool () and modify the path to trace the glass, like so:

When we're done modifying our Path, we can goto the Paths Panel (Window > Paths) and right-click the Path we just created and choose Make Selection. We don't want to feather the radius.
Once we have our selection, we can go back to our Layers Panel and copy from the original layer and copy the selection into a new layer. Our Layers should now look something like this:

Once we've pasted into a new layer, make the selection again by Ctrl-clicking the new layer. Make another new layer and paint the selection in Black:

Next, goto Filter > Texture > Grain. Choose Grain Type Vertical and Intensity 100. Play with the Contrast until you get something like this:

Now goto Filter > Artistic > Smudge Stick. Play with the settings until you get something like this:

Then goto Filter > Blur > Gaussian Blur, and give a small radius (1 - 1.5), then finally, Filter > Blur > Motion Blur, with a Angle of 90 and Distance of 10-15px. Now goto Image > Adjustments Levels and adjust the pointers until we have something like this:

Now we need to adjust the lines to fit the shape of the glass. We can do either Filter > Liquify or Edit > Transform > Warp. We should end up with something that looks like this:

Next, goto Select > Color Range and use the eyedropper tool to select Black in the image. We should then get a selection of the Black on this layer:

Now hide this layer we've been working on and choose the duplicated glass layer. Goto Filter > Blur > Gaussian Blur, and choose around 3px. Then goto Image > Adjustments > Hue/Saturation and choose around +10 for Lightness. Finally, goto Filter > Noise > Add Noise and choose around 3% Uniform, Monochromatic. You should have something like this:

You may find that you need to trim some of the condensation lines. Remember, the values used in this demonstration may differ on your image. Use PhotoShop to its full potential and experiment yourself.
Here is our final image: