Mass Effect 2, Ashley © BioWare/EA.
You are free to use this reference however you wish. You can also download the full size version.
Note: Unfortunately, due to how the textures work, there appears to be a line or difference in shading around the face from certain directions where it joins the top of the head or neck. There is nothing I can do about this. Some other models also exhibit this effect.
Personal note: No, I have no idea why she looks a little tipsy in some pictures, that's apparently just the way BioWare animated her. In some other pictures I have seen around the internet she even looks cross-eyed