Have you mocked your screens up? Typically it doesn't make sense to just "make things smaller" for mobile. There are a few ways to go about implementing this, but I hate to see people wasting effort. I always just do some quick drawings on paper that are super rough, but just get the basic layout idea first.
When it gets time to implement, you can use skinning to provide different looks for different devices, but you will still be limited by the layout you did for your page. It could be a lot of work to do it through skinning alone, but some of the stuff is already done for you, and may look good without any extra work, but don't think you will get away with no skinning to do. You could also use switchers to provide different page content, if you are not comfortable with going really deep into skinning and messing with geometry, which is not recommended.
Usually the page layout for a mobile device will be completely different than the one for a desktop machine.
If all you want to do is make thing "bigger" than skinning based on platform is the solution.
In terms of achieving a single layout that adopts to smaller screens see this: