One of the most common retouching catastrophes I see on a day to day basis is an overzealous attack on eyes. Like over-baked HDR, obnoxiously over-retouched eyes have become almost ubiquitous among less experienced retouchers. Awareness is the first step to recovery, so in the spirit of painting a big obvious flag in front of all of you eye ruiners out there, take note. Your models will love you if you learn how to make their eyes look amazing without making them look like they belong in an episode of "Stranger Things."
Stop Making Eye Whites Glow
Why is it that so many photographers want to make the whites of the eyes perfectly white? It is one of the most obviously obnoxious things that you can do. I know that your goal is to retouch a model into looking like a perfect version of themselves, but in what world are perfectly flat, white eyes a reflection of a perfect human? You would need to stick lightbulbs in their eyes to achieve such an effect in real life. Stop screwing with the tonality of eyes whites, they have shadows because they are round in shape. By flattening out the eye as if it has no three-dimensional shape not only do you make the image look incredibly strange but you also are making the eyes look cartoony. Furthermore, it's important to remember that a viewer instinctively is drawn to the brightest point of the image; if you are making the eye whites so bright that they distract from everything else, there is a problem.
Fixing up eye whites is pretty easy and requires very little special attention. If the model has too many veins, simply clone them away the same way that you do blemishes on the skin. If the model's eyes are too red then adjust their color or reduce their saturation the same way you fix discoloration in the skin. Do not reduce saturation to zero; even the most perfect eyes don't become magically black and white.
Stop Making Irises Look Like They Belong to a Possessed Alien
The iris is often the most important part of a portrait. It conveys the most expression and is what drives the most connection to the viewer. When you make eyes look like they are straight out of that unfortunately poor film, "The Host," you do succeed in drawing attention to the eyes, but instead of drawing attention to beauty or character you draw attention to the impossibility of the effect which shatters the credibility of your photo. Increasing the brightness of irises can be an incredibly helpful tool but don't overdo it. Learn restraint and pull back the opacity of your effect heavily. The goal should be to draw attention to the eyes but the viewer should never actually notice the effect consciously. Rather, they should only think about how amazing your model's eyes are.
Stop Changing Irises to a Uniform Color
As retouchers we often encounter situations where changing the hue of an eye can be a strong asset to a photo. Moving to a rich blue or green can be a beautiful change, just ask Peter Jackson; Frodo wouldn't have been Frodo without his ridiculously blue eyes. The biggest mistake many retouchers make when trying to accomplish an eye color change, however, is that they simply mask the iris on a hue/saturation layer then hit that magnificent colorize button to uniformly make the entire iris the exact same hue. At a glance, it works great but there is a strangeness to it that isn't quite right. This is because no eye has a single uniform tone. Even the bluest or greenest eyes have a variety of green or blue tones within them. In order to address this, the easiest solution is to pull back the opacity of your adjustment layer. Not only does this make the effect more subtle, it also allows the original color of the eye to subtlely mix with the colorize layer so that you are able to retain a diversity of hue within the iris. While we are on the subject, also don't over saturate eyes when you do this. A pupil shouldn't look like it is filled with Kool-Aid.
Point Light Sources Make Horrible Catchlights
This is a major pet peeve of mine that you probably will struggle to unsee now that I'm about to point it out. There are a huge array of situations that can cause a tiny specular highlight to reflect right in the middle of the pupil. The most common cause is an unmodified speedlight or another light source within line of sight of the model. Always clone them out. Bigger catchlights do a great job of adding a beautiful twinkle to the eye but tiny little specular highlights only make it look like there is some sort of white dust right in the middle of the model's eye. This is very distracting to the viewer as we are so instinctively mortified by objects in our own eyes. Most viewers won't be able to tell you that it is that little white dot that is distracting them but they won't feel as connected to the photo until you remove that nasty little highlight.
Learn to Step Away From the Computer
While working an image we tend to desensitize our vision to the effects that we have applied to that image. Thus, we tend to apply thicker and thicker layers of effects just so we can still see that those effects have been applied. This phenomenon is at its most severe when it comes to eyes. Before finalizing images always make a point of spending some time away from your computer to then re-evaluating your effects before doing your final export. Most of the time you will find you have overdone it and need to pull back the opacity of the effect to create a more natural blend. Taking the example image used throughout this article, my original edit for it was a tad over the top — though I never went quite as far as any of these obnoxious examples that I had to shatter my heart. Upon re-evaluating, I heavily drew back the impact of the effect and am much happier with the final image as a result.
Like almost all aspects of retouching, getting great eyes is about perfecting subtlety. The eyes are such an important aspect of a portrait that you need to learn how to get them right or your photography will forever suffer. Study how light interacts with the eye and learn how to augment in a way that looks natural. Unless you are literally doing a special effect on a character that is supposed to look like an alien, a general goal to not make your model look possessed is probably a good one to follow. The best advice I can offer is to always pull back the opacity of an eye effect. In this regard, too little is always much better than too much.