Make them once - use them again & again.It is fun to toss in some texture to give my designs for products some zip :-) It can be as simple as just having a layer of texture (shown in the Yorkie notepad above). Or I might only have texture in part of the image. I added swirls to the top half of the background in the pear paper plate above. (Click image to see it larger).
Not only does it make the image look richer - I use textures that I have made with more than one collection. I like that it speeds up designing/mocking up products!
Here is a good video about making photoshop brushes. It has a couple tips for the magic wand tool too.
There are LOTS of free brushes on the internet - be sure to check that is OK to use for commercial use. Some are only free for personal use.
Let me know if you are a photoshop brush fan :-D