I think where one's design skills can be considered lacking, as I very much consider my own, simplicity becomes increasingly important and attractive as a design philosphy.

Plenty of white space, clear typography, showing only what is needed, and aligning vertical and horizontal edges helps hugely.

Two tools that also help enormously: http://www.906.gs - a grid system for layout and http://www.colourlovers.com - Colour Lovers for awesome colour palettes.