work should done with divs/css (XHTML) no tables try to use repeated image background if it is a uniform gradient and commit with the font size, font type and font color in the psd if you cant you should get back to me for advise. minimize the use of png images, use gif when the images has limited numbers of colors like logos for examples and use jpg for fully colored pictures and most important is to simulate the same look and feel of the original design. also you should measure exactly the paddings and margins in the psd file and apply them in the same manner and making sure to maintain nice quality when it is about optimizing the sliced images.
everything should be cross platform, cross browser compatible using W3C standards