It’s not hard to find images to use online – just use an image search. This works well, but it’s worth noting that doing so isn’t necessarily legal. Most of the images you can find this way are owned by their original creators. This likely doesn’t matter if you’re only using something for private use, or even a school assignment, but if you intend to publish a work you need to make sure all rights are cleared.
If clip art appeals to you for its retro feel, you might also like pixel art. You can create some yourself with pixel art tools The 11 Best Pixel Art Tools to Create Pixel Perfect Artwork The 11 Best Pixel Art Tools to Create Pixel Perfect Artwork Do you want to try your hand at creating pixel perfect artwork? These pixel art tools will help you get started. Read More .
This is TERRIBLE! Besides being able to edit vector images like Will mentioned (which is important for those of us who don't have graphic artists available to create custom images or the budget or time to buy that service ad hoc), you could also search for style "families" (different graphics that were all in the same style). There was a huge range of files and styles in the collection and it was much faster to find what you need than to do a Bing search. Plus, you knew that everything there was free and free to use, without having to worry about CC license issues.