There is an app in WP store called TileScreen, which can help to customize your Windows Phone 8 (not 7.x, sorry) home screen. There was a review post last week on WMPoweruser. Many people are confused with concept and how to use it. As the developer of the app, I'd like to post some tips. Hope this helps.
1. TileScreen, as an app, does NOT change home screen layout or live tile sizes automatically.
This app is about create and share designs and ideas about how you can make your home screen fun. Microsoft don't provide APIs to do it automatically, and they shouldn't. We will have some problems to deal with if they do. So, basically to use the design on your phone home screen, you have to do it manually. I hear you say, that sucks. Trust me, it doesn't. Experimenting the pattern and organizing tiles is a lot fun. You do that when you are bored, have too much time anyways.
2. If you create your own, keep it clean and practical.
The goal eventually is someone is going to use your design on their home screen. So, it has to be practical. For example, some use a whole lot of small tiles in their design, it may look good, but if you that on your home screen it will look messy.
3. Use as many medium sized tiles as you can.
That's how you can make it clean. Many don't know to create medium sized tiles in the design page: Use pinch and zoom on adjacent same colored tiles to create or break medium sized or large tiles. See pic below:

4. Colors don't matter.
The color buttons are there for cases when really need a second color. Generally you should use only one color, sometimes a second or third color is desirable, but keep it minimum. Reason is you don't have much color varieties in your home screen. Most of them are theme color. A few of them have different colors like the Office is read, the Xbox is green.
TileScreen was released only a week ago, there are bugs. I have been fixing them. It is generally functioning now. If you have questions, requests, I can answer them here. You can download TileScreen from here: TileScreen | Windows Phone Apps+Games Store (United States)

1. TileScreen, as an app, does NOT change home screen layout or live tile sizes automatically.
This app is about create and share designs and ideas about how you can make your home screen fun. Microsoft don't provide APIs to do it automatically, and they shouldn't. We will have some problems to deal with if they do. So, basically to use the design on your phone home screen, you have to do it manually. I hear you say, that sucks. Trust me, it doesn't. Experimenting the pattern and organizing tiles is a lot fun. You do that when you are bored, have too much time anyways.
2. If you create your own, keep it clean and practical.
The goal eventually is someone is going to use your design on their home screen. So, it has to be practical. For example, some use a whole lot of small tiles in their design, it may look good, but if you that on your home screen it will look messy.
3. Use as many medium sized tiles as you can.
That's how you can make it clean. Many don't know to create medium sized tiles in the design page: Use pinch and zoom on adjacent same colored tiles to create or break medium sized or large tiles. See pic below:

4. Colors don't matter.
The color buttons are there for cases when really need a second color. Generally you should use only one color, sometimes a second or third color is desirable, but keep it minimum. Reason is you don't have much color varieties in your home screen. Most of them are theme color. A few of them have different colors like the Office is read, the Xbox is green.
TileScreen was released only a week ago, there are bugs. I have been fixing them. It is generally functioning now. If you have questions, requests, I can answer them here. You can download TileScreen from here: TileScreen | Windows Phone Apps+Games Store (United States)

