First off, when requesting a banner please do so in the following manner.
Text: What words you want on the banner
Size: How Large or small you would like your banner note, 600 width by 200 height is max.
Colors: Blue and Red, or Black and White Etc..
Render: Provide a link for specific, or general type, such as halo render.
Now you may ask,
NOBODY MAKES ME A BANNER WHY NOT????
The reason most people aren't making you a banner could be for one of a few reasons.
1. You may have just joined the forums, if you have only a handful of posts, people aren't going to make you a sig because you haven't been around to show your activity. Try and be active and an intelligent poster for a few weeks first before requesting.
2. If you make in-coherent, spam, or rude posts, chances are people won't see you as deserving to get a banner. Remember banners aren't always easy to make, some can take up to 2 hours or more, and people wont spend 2 hours to make a person a banner who is frivolous.
3. Banner makers aren't always active, so leave a thread be, and wait for someone to respond, if nobody responds, please don't go out, pm'ing every single banner maker you see and posting in every banner shop.
If nobody responds to your request, leave it for a week, and then bump it, rather then pm'ing everyone.