Quote: "I know to look for licenses when down loading textures but what if it was lets say a photo from a google search, or a picture from a catalog. I really need to know this before I start spending too much time making media I'm not allowed to sell."
you've answered your own question. If you know to look for licences, then you know that if a licence says,
Quote: "you may use this in any media form for commercial or non commercial "
you can use the media
if it doesn't say you can use it for commercial, you MUST get permission from the creator before selling.
simple as that.