A great way to personalize your Windows Phone 8.1 device is a custom start background. You are no longer limited to using the 20 or so accent colors as the default tile color. You can now select an image file to use as the background.
When you select an image, it becomes a fixed background. When you scroll the start page, the location of the image stays fixed, Most of the bundled apps will use a transparent background when a background image has been select, allowing the background image to show through.
This allows you to personalize your phone even more to your tastes. You can use any image that is on your phone or accessible through OneDrive. I have found that using darker, muted colors worked well, providing a good contrast with the foreground tile color.
You can select the image under “start+theme”, in the settings app. You should see something like this:
When you click choose photo, you get the standard image picker and you can select an image that is on your phone or in your OneDrive account.
The image that I used here is from the DeviantART web site. I did a search on “grunge” and selected a couple of images that I liked. This image is named Hazard Grunge and is from the user named WheelOfFish.
After selecting the picture, you will then select which area of the picture to use as the background. Since the image will mostly likely not match the aspect ratio of your phone, you select which part to use.
With the final result, you get a much cooler looking start page. And it looks more like your phone than just another Windows Phone.