There are a lot of tutorials on getting the “tilt-shift” effect in PhotoShop, essentially making things look like toys. Here’s Manhattan Island, for example.

I want to show a different technique than the one usually offered. This one is more useful when the image is a bit more complex. I’m sure it’s not original with me but here it is anyway. As usual, PhotoShop CS6 running on Windows 7 Pro 64-bit, with a Wacom Bamboo Fun for painting.
The original image is this, which can be downloaded HERE.

The typical instruction I’ve seen is to activate Quick Mask mode, and use the Gradient Tool to mask off a vertical band of the image.

Then, as usual, you exit Quick Mask mode, go into Filters, Blur, Lens Blur and apply. Unfortunately in an image like the above, where you have one element (the trees on the left) which goes all the way up the side of the image, this gives you a result like this:

As you can see, the illusion of tinyness is rather spoiled by the slab of trees that are tinified when they should be blurred. The trees give it away–they’re blurred, then they’re not, then they are…hey, this isn’t a real toy!
So in the case of an image like this, I still go into Quick Mask mode but use the Paintbrush instead. Using a soft brush, you can paint the entire bridge and the trees which ought to be in approximately the same level.

Which gives a much more “realistic” result.

As previously noted, I’m sure this isn’t original with me, and there are probably far easier/better ways of getting more impressive results. Buy, hey, you get what you pay for!
As always thanks for stopping by.