I have a photo from Operation Photo Rescue and have selected the yellow tint with the color selector and placed it on it's own layer. Upon closer inspection, there is a yellow hue that I cannot seem to remove. Any suggestions I could try?
The color problem is in the face (nostril, side of nose, shadow from hair...)

You could try a controlled Hue/Saturation adj, you could try a Selective Color Adjustment, you could use Advanced Blend If Layer Style, you could take the image into LAB mode and ground the B channel which will kill the yellow dead. And there are a bunch of other ways. If you post the image or a sample of it, you can probably get some specific advice to your problem.
Regards, Murray

how can I post just a sample of the layer?

How do I ground the B channel?

might try this too:

select the area>image>adjust>selective color>yellow channel>add blue

Michelle, in LAB color yellow is represented by the positive half of the B Curve. If true shades of yellow need to be removed, then locking down the Blue half of the B channel and flattening or "grounding" the top half will turn all of the yellows to white or black or grey depending on the lightness of the color. This is very useful for some situations depending on what you need to do to your image. Below is and example where 4 primary swatches are present. The curve which is applied affects only the yellow (here a medium yellow) which is neutralized (gray at the same luminosity) resulting in the 3rd image. The other colors are unaffected. If youy are still having trouble, you may want to post the image you are working on for additional suggestions.
Regards, Murray

Here is a part of the face. As you can see, her nostril has a yellow hue I can't seem to get rid of. If I use LAB mode, how do I convert back to rgb?

Michelle, LAB is not the solution you want to use here. Here are two solutions of many; the 1st being very quick, the 2nd being more precise but a bit longer.

1. Choose the Eliptical Marquee tool and draw an oval shape encompassing the nostril and larger than your yellow area by approx 1/8". Then do Ctrl+Alt+D (or Select>Feather) and choose a value of about 3 or 4 pixels (you may need higher if you are working on an image of higher resolution).
Next Image>Adjust>Selective Color (Alt+I+A+S). When the dialog box comes up, select the yellow channel, then move the yellow slider to the left a little at a time until the yellow is gone.

2. Technique 2 is a Hue / Saturation adjustment Layer:
As above make an eliptical selection encompassing the nostril. Now from the button at the bottom of the layers palette, click on add new layer and select a Hue / Saturation. When the dialog box comes up, select the Yellows from the pull down menu. Move the lighten slider a small amount to the right to brighten the area just a little (my taste only), then move the Saturation slider to the left until the yellow disappears to your liking. Don't worry about the area around the nostril which has gone gray. Click OK.
Now with the Hue/Sat layer still active, select a small soft brush, color black, opacity aroung 20 - 30% and carefully paint over the areas around the noise which you did not want to be affected by the Hue/sat adjustment. As you paint you will gradually restor it to its original color while maintaining a smooth transition to the nostril. Attached are a couple of snap shots of this method.

Regards, Murray

Here is a part of the face. As you can see, her nostril has a yellow hue I can't seem to get rid of. If I use LAB mode, how do I convert back to rgb?

ohhh, if its that simple, just use the sponge tool set to desaturate, or the burn tool.

dont mess with lab if you dont have to.

Thank you so much Murray! I'll try that today. This poor photo has many problems. Perhaps you could help me with some other problems it may have.

After reading about the LAB... I did a bit of research on the web and found this plug in called Curvemeister. I was wondering what you thought of this application.

Again, thanks for taking the time to help.
Michelle

Michelle, . Curvemeister has some nice timesaving conveniences and more colorful user interfaces over PS. Howver, the curves in PS will get you to the same end point. My recommendation for those learning PS would be to gain a solid proficiency with PS curve tools first because it will force a better understanding of the fundamentals of curves and color correction. After becoming proficient at PS curves, one can then try out the Curvemeister demo and decide it it provides the additional productivity enhancement to justify the extra $80 for the plugin.
Regards, Murray