When I first started Bubele, I created my own print files using Photoshop and 2 simple patterns: polka dots & stripes. I taught myself how to use Photoshop by searching for tutorials online for what my needs were. When you are designing prints for clothing, you need to make sure you 1. Create a seamless pattern 2. Figure out what size you want the print to repeat. I would always start with a 5 x 5 inch square in Photoshop with a resolution of 350 pixels/inch. You need your prints to be in high resolution for the company printing your fabric! You can always save in a lower resolution after if you need it for your website.
After a couple seasons, I knew I needed a wider variety of prints so I started purchasing prints from sites like istock Photo. Some of my most popular selling prints came from here, like this Floral pattern or these Animal Prints. If you don't like the colors in the print file, you can change them in photoshop, but I suggest using Adobe Illustrator where it is easier (more on that later).
There are many sites now where you can buy stock patterns (just make sure they are seamless). I have several hundred print files saved that I have not even used yet! I wait until a stock photo site has a deal and gives away free credits and download my favorites! Tip: start organizing your prints in files now because it is easy to lose track! Most sites allow you to go into your download history if you do lose track- see below :)