An interesting post from Googler Gavin Dolan via Bokardo shows a graph that illustrates the relative merits in redesigning parts of your site in relation to the ROI for each action.
It seems that you will gain a greater ROI from redesigning your forms which is most likely due to a greater conversion of visitors into customers/clients due to forms becoming less laborious to fill in and weeding out the irrelevant data that forms often request. This is an area of web design that is often overlooked but good form design is of the utmost importance to the goals of most site owners.
This is not to say that redesiging the homepage and landing pages is not also important as they too provide an impact to conversions but it is good to be aware that form redesign has the greatest impact on ROI. This will be especially true for sites which have a high number of visitors but low number of conversions.
