If you don't want to use a professional, there are a few things you can do to make sure you get a semiprofessional headshot of yourself.
I'm all about going the DIY route whenever possible, but there are some things that are best left to experts, and professional headshots may be one of them. Don't get me wrong, not everyone needs a headshot, but nearly every professional requires a passable photo of themselves for use on social media. Here's how you can get around having professional headshots taken without succumbing to some seriously amateur-looking photo mistakes.
Don't try to replicate a professional photo shoot
If you're not going to pay a photographer to have a headshot taken, don't try to replicate a professional headshot yourself. Unless you're a skilled photographer, or you have a friend who is, trying to mimic a professional picture will likely miss the mark and draw attention to technical flaws in the lighting, composition or overall exposure.
Instead, opt for a photo that has the look and feel of a snapshot. It's better, even on a professional network, to have a photo that's nice-looking (but clearly not a headshot taken in a studio) rather than a photo that looks like someone's poor attempt at taking a "professional" photo. A snapshot shows that you know the difference between the two, while a poorly executed DIY headshot makes it seem like you can't tell the difference, even when others likely can.
Use natural lighting
Whether you're taking the photo yourself (hopefully with use of a tripod and remote shutter release) or employing a friend, your best bet for getting a snapshot that you don't have to filter into oblivion is shooting in indirect natural light.
If you've had difficulty taking good photos in natural light in the past, it’s likely because you were shooting when the sun was high in the sky and the sky was clear. When there is a strong light source coming from just one direction, the options are essentially to either shoot with the subject facing the light (squinting), which will result in a blown-out image, or have them angled partially or totally away from the sun, in which case extreme shadows will occur (often under the eyes and near the edges of the mouth, which is typically unflattering).
There are three basic ways to get around harsh shadows while shooting outdoors. The first, and possibly easiest, option is to wait for an overcast day. Cloud cover acts as a natural light diffuser and makes it very easy to capture images without harsh shadows. Shooting in a partially shaded area is also an option, but it requires more expertise. That's because areas that are too dark or have too much contrast may not produce ideal images.
Finally, you can attempt to take advantage of magic hour or golden hour. Magic hour, a term often used in cinematography, is just before sunrise or just after sunset, while golden hour, a term frequently used in photography, is the time just after sunrise or just before sunset. During magic hour, light is diffused with an even golden tint and lends photos an ethereal feel. During golden hour, light is diffused with a reddish tint, which can also be attractive.
If you’re not confident in your photography skills, stick to shooting in natural light on an overcast day.
Edit sparingly + avoid cropping if you can
If you're going to use a nonprofessional photo as your headshot, choose one that doesn't need a tremendous amount of cropping or editing. Cropping a photo down (or resizing it) so it fits within the confines of a specific site (ahem, LinkedIn) is fine, but cropping out a large group of people to capture a close-up of your face is likely to result in a fail. If you're going to use an existing photo for professional social networking, choose one that's just of you.
It's also advisable to go easy on the filters and image-editing tools for your headshot. Even Photoshop power users often go overboard editing images, and amateurs doubly so. Too many people approach image editing as a cure-all to fix every imperfection in an image, but that's not really what it's for, especially when it comes to headshots. Editing can be efficiently employed to remove unsightly blemishes and correct minor features, but overediting often results in unnaturally saturated colors and flat uncanny valley-like faces that, while totally blemish free, also look a bit inhuman.
Using filters also isn't best practice for most headshots, and using them to compensate for poor lighting or exposure should be avoided at all costs.
When in doubt, just pay for it
If the photos you're getting from DIY sessions consistently require lots of editing, suffer from harsh lighting or poor exposure, or otherwise just don't look right, pay a pro. Professional headshot services aren't all that expensive, and if your work requires you to have a visual online presence, it's worth shelling out a couple hundred bucks for a polished picture of yourself.