PLEASE NOTE: These actions are pixel based, which means that they will appear differently on different document sizes / resolutions.
Play around with the multiple action options to choose what you think looks best!

1. Watch the Youtube Overview and How-to via the link above for the best way to learn.
2. Install the Halftone Automator action set (instructions listed below)
3. Open the photo you wish to halftone into Adobe Photoshop. Be sure the Actions window is open (Window -> Actions). Keep in mind that higher quality photos with excellent contrasts will yield the best results.
4. Click on the layer that you want to run this action on. Keep in mind that this action will only run on the selected layer, and will bring that layer into a new document as not to overwrite your images.
5. Open the Halftone Automator action set folder to see the list of actions you can run, and select the action of your choice.
6. With your layer and action of choice selected, hit the "play" button in the action window.
7. Adjust the brightness and contrast of the image as desired, keep in mind lighter areas will result in less dots / lines, and darker areas will result in more. Well contrasted images tend to yield the best results.
8. On the Bitmap dialog box change the output resolution to match the input resolution. 300 PPI is selected by default, but not matching the input resolution to the output resolution will result in the image being enlarged or shrunk depending on if you enter a larger or smaller resolution than the input. Drastically enlarging or shrinking the image via this method may result in the action causing Photoshop to be unstable, so it's best to always match the input and output resolutons.
9. On the next screen just hit "ok" and leave the settings as is.
10. Your halftone is now complete and in a new document, and on a transparent layer (the top one of the two). You can drag this new layer into your previous document, or change the color using hue / saturation (CTRL + U on a PC or Command + U on a Mac.) You could also apply a color overlay using the Fx button in your layer palette.
11. Play around with the various actions and your image's contrast levels for a huge amount of variety.
12. Please note that pure white elements will not halftone.

1. Select the .atn file that was included in the download. Press CTRL+C or COMMAND+C to copy it.
2. Navigate to your Photoshop Actions folder on your computer (Program Files (or Applications)\Adobe\Photoshop CS\Presets\Photoshop Actions) (You could load it straight from the download folder, but it’s a good idea to keep a copy of all your actions in the Photoshop Actions folder.)
3. Press CTRL+V or COMMAND+V to paste the action into the Photoshop Actions folder.
4. Open Photoshop
5. Open the Actions window (Window -> Actions)
6. In the Actions window, click on the little arrow button on the top right corner of the Actions palette and select “Load action”.
7. Look for the ATN file you just saved when the pop up file browser comes up
8. Once you’ve found the .atn file, select “Load”.

You can also simply double click the action file, which should bring it into your actions palette. To view this palette to go Window -> Actions from inside Photoshop.