I also recomment you agent doing an estimate of market value/CMA on the property you're looking at...Try to understand why the listing is at the current list price. That will help you understand your options and a strategy path for your offer. In the end, talk with your agent.
All this is trying to paint a picture of the desirabily of Corte Madera. The best thing to do, for Corte Madera and other areas, like the pros mentioned below; is to find a reliable Realtor who are familiar with the area, to provide you with the comp and an analysis about the specfic property you are interested in and go from there.
There is never a set formula for offering more or less for any property in any area at any time. Each property is unique.