tips on developing resolution independent application

Question

Is it a good practice to find the workarea measurement and set some properties in code so that it could be bound to Control's margin or height/Width properties in xaml?

I do this so that my window would resize according to the available workarea.

const int w = SystemParameters.WorkArea.Width;
const int h = SystemParameters.WorkArea.Height;

public Thickness OuterGridMargin { get; }

MainViewModel()
{
    OuterGridMargin = new Thickness(w/5,h/6,w/5,h/4);
}

xaml:

<Grid Margin="{Binding OuterGridMargin}" />

I do this for some outer containers so that the layout would not be messed in lower resolutions. Currently I work at 1600x900 res(96 dpi) in a 20". My application is gadget like and does not have the regular window.

I want to know if there are some alternative approaches.

A search of [wpf] resolution]1 gives a lot of questions addressing similar problem but still I'm stuck and not able to come to a conclusion how to achieve a good resolution-independent layout.