For this tutorial, you will need an image or portrait to work with.
1 - In Illustrator, create a “New Document”. Go to File > Place and navigate to where the image you wish to use is stored. Select it and click “Place”.
2 - Select your image and center it by clicking on the “Align Horizontal and Vertical Center” buttons on the Top Menu. Make sure that “Align to Artboard” is selected. You can drag a “Guide” to the “Center” of your image to divide it in half. Then, you just need to make one half of the vector and use the “Reflect Tool” (O) to mirror it to the other side.
3 - Lock this Layer by clicking to the left of its thumbnail and bringing out the small Padlock icon. Then, “Create New Layer” by clicking on the button at the bottom of the “Layers Panel”.
4 - Select the “Pen Tool” §, choose a bright contrasting color for the “Stroke” and no “Fill”. Start creating outlines of the different parts of your image (in our case the eye, hair, etc.). We also created an “eyebrow” shape since the image doesn’t have it.
5 - Now, make “Triangles” all over your image. It’s not necessary to close the “paths”, just click “Enter/Return” to stop the Path. If you close a Path, click the “V” key to get the “Selector Tool”, click out of the path and then go back to the “Pen Tool” and start again
6 - Once you are done go to the “Pathfinder Panel” and choose “Divide”. If some of your “Strokes” disappear, just select everything and choose a “Stroke” color again.
7 - To work better with lines, go to View > Outline (Command/Control + Y) and start using the “Direct Selection Tool” (A) to click on the “Anchor Points” that appear out of place and fix them. Do this all over your image.
8 - Once you are done, go back to “Preview Mode” and check out your Paths.
9 - Select the “Eyedropper Tool” (E). In the “Layers Panel” click on the small arrow to the right of your “Thumbnail” to show all the different “Paths”, then click right next to the small circle on the right. A colored square should appear to show you that that “Path” is selected. Then, with the “Eyedropper Tool”, click inside the “Path” to “Fill” it with a color from your image.
10 - We noticed that the color of our “Strokes” was too similar to the one of the “Selection” so we changed it. Also, some of the overlapping created small “Paths” that now appear as “Filled” with color, just delete them.
11 - Keep filling all the triangles in your “Artwork” and if you notice some gaps you can fix them with the “Direct Selection Tool” (A).
12 - Check out your work.