What to Look For

When it comes to stock images there is no better time to be picky. With both free and purchased stock, be discerning. Once you start being picky about what stock you use, and even better when you start using premium stock, you will notice your quality of work will increase a significant amount. Better ingredients means better results. 

Clarity

You want a crisp clear image with a very very low amount of noise, no motion blur caused by a shaky camera, and completely no artificial effects and edits. Noise is the most common issue, but also the easiest to deal with (to an extent) as long as the image is a good size. Which brings us to our next quality to look for.

Size

The bigger the better. The bigger it is the easier it is to add details, fix defects, and overall just a million times easier to work with. In fact, unless you are a 100% web only hobbyist low resolution images are basically unusable. There is nothing worse than seeing an amazing stock image on DA just to find out it's only 1200px tall. 

Make sure to avoid artificially enlarged stock photos. When an image size is increased in an image editing program the pixels become distorted and destroyed.

Originality 

Avoid the mega popular stock images as much as you can. Again think of stock as an ingredient. You want fresh and new ingredients. You don't want someone to look at your art and think "I have seen this 100 times before" or "This reminds me of that other image I saw that used this model". I personally even avoid using mega popular models.

Finding Balance

Now with paid stock all these things are guranteed to the fullest, but when it comes to free stock you are going to have to find a balance that works for you. I am most picky about any image that is going to be a core part of the overall piece I am making. Usually the model.  I am much much less picky about originality with small side objects, I don't have to worry about an image having a lot of noise if I know it's going to be blurred in the final image anyway, and size doesn't matter if in the image is going to be small.

I will sacrifice some quality, usually noise, if the  stock image is incredibly original and an extra large size. Or if the stock  really is the perfect image for what I want to do and is of incredible quality then I will sacrifice originality. It all just depends. 

The Right Usage Terms

You can't use every image anyway you want. There are terms set out by the photographer that you must follow. On Deviantart every stock photographer writes their own terms, such as requiring credit, or only allowing the image for personal non-commercial use. You can often find their terms in the description of the image or on the artist profile. 

Premium sites such as 123rf have two different licensings - "Standard" and "Extended". When creating a piece of work that will be resold, such as a book cover, then you will need to buy the "Extended" license. And while premium stock often times does not require credit, it is a kind gesture to name and credit the photographer of the stock photo. 

Where to Find Stock

There are the right places to find stock, and the wrong (and illegal) places to find stock. Respect the medium, other artist and yourself by going to the right places. With the amount of free to use images there is no excuse to not use legitimate resources.

Free

Deviantart Resource Section  | Cgtextures  | Morguefile | Freeimages | Pixabay | Unsplash | imageafter
Personally, my two favorite free sites are good old DA and Cgtextures .

Freeimages was formerly known as Stock.Xchng. Due to a change in their terms of use the overall rule on DA is that if you use an image from the above site then you must have the photographer's written permission. Better safe than sorry? 

Paid 

shutterstock  | fotolia | 123rf
There may be no better price than free, but with paid resources you are getting the best of the best guaranteed. The best quality, the best size, and the best models shot by the best photographers. You are getting the best so that you can then offer the best. 

The Not Okay Places 

Google images is not a valid resource. It never had been. Wallpaper sites are not a valid resource. Ever. 

DA Stock Image Feature