How To Avoid Grainy Looking Photos
"I have a question, and I'm hoping someone can help! I absolutely LOVE these presets. However, I'm worried that some of them may have a lot of grain when I put them on my pics... I reduce it sometimes and also bump up the noise reduction... however when I zoom in especially around eyes... it's very noisy. Is it me and my settings? I just worry someone is going to want to blow up one of these pics on a canvas or something and the quality won't be good enough!"
I've had a few of you ask what can be done about the added grain after running presets. You might have noticed that on some of your image the presets come out absolutely perfect and on others, you see (especially if you zoom in) much more grain and noise (ick!)
So where does this graininess come from and what can be done about it?!
The result of this added noise is a combination of your settings + the preset settings. When you sharpen an image in lightroom, it looks for little details and contrast. When you shoot an image in low light you often have to increase your ISO (In Digital Photography ISO measures the sensitivity of the image sensor. The same principles apply as in film photography – the lower the number, the less sensitive your camera is to light and the finer the grain. Higher ISO settings are generally used in darker situations to get faster shutter speeds.)
Once you run the preset, you might notice the additional sharpness can also add some unwanted grain.
So what can be done?
UNDERSTAND WHAT ISO IS
Understand ISO; If you are shooting a session and have to increase your ISO (there's really no way around it unless you were to underexpose your image...which is something I often like to do) then keep in mind to NOT over sharpen your images in lightroom. Pull that sharpness slider back down. You can also try to increase your noise reduction, but I've found that what works best is simply to zoom in, see what it looks like and keep the sharpness where it still adds some more details, but doesn't overdo it by adding all that grain. Understand that as you are shooting that if you have to increase your ISO (you're most likely not going to notice any grain on the back of your camera screen and will only see it once you have it on your computer and zoom in close) that this is something you will need to work with afterwards.
DONT BE AFRAID OF UNDEREXPOSING A LITTLE
Don't be afraid of underexposing a little bit. This is a personal choice, and I realize that in books it's the "wrong way" to shoot...but it gives me the results I want to this is one of the rules I like to break...often.
When I have the choice of underexposing my image OR increase my ISO, I will ALWAYS choose to underexpose my image. It is easy to lighten up a RAW image in Lightroom. Once you shoot an image with a higher ISO that grain is there to stay, and not much can be done after.
Below is an image from my wonderful friend Adrea from Andrea Krey Photography who uses the same method. You can see how underexposed her before shot is...and that there is virtually NO grain in the after. She shot this image at ISO 100 so although it is underexposed, brightening and sharpening it up Lightroomtroom turned out absolutely beautiful. Only when I pushed the sharpen slider all the way over did a little bit of grain start to show up. This shows that you can absolutely underexpose your images and still get them bright and sharp afterward.
BEFORE SHOT
AFTER - NO SHARPENING 
AFTER - SHARPENING WITH PRESET
AFTER - FULL SHARPENING
FINAL IMAGE
WORK WITH WHAT YOU HAVE
Sometimes you just have to work with what you have. The image below is from a session on a very overcast day with VERY little light. I had to underexpose my image (just as the above shots), however even when working in this limited amount of light, I HAD to increase my ISO to keep my settings where I needed them to be. I shot the image at ISO 640 (a whole lot higher than the ones above). You'll notice that the details look much different in these and that by over sharpening the image it brought out a whole lot of grain. In this case, I will need to play around with my sharpness and bring that down to where it looks good.
AFTER - NO SHARPENING
AFTER - SHARPENING WITH PRESET
AFTER - FULL SHARPENING
Keep in mind that when working with presets it's always a good idea to zoom in, take a look and take the time to customize your sharpness. There is no way for a preset to know what your ISO is and what kind of light you are working with so this is one of the things you have to keep an eye on as you edit your work. Understand your settings (especially your ISO which is so often overlooked) and know what it will look like when you are finished with post processing.
As always, I'm happy to answer questions, offer tips and help you along the way.