Research the building's history. Doing this provides valuable information on how to best restore the features, colors and designs of the building from a modern perspective while taking into account the historic architecture of it. The Old House Journal remarks that "later alterations are significant to the building; in other cases, the alterations may be without historical or architectural merit, and may be removed in the rehabilitation". Research will also help to plan how the restoration of the interiors and exteriors can be best integrated.
Get inspiration. Online magazine Victoriana suggests using Google Maps Street View to scour the streets of San Francisco (or virtually any other town/city in the world renowned for Victorian architecture, for that matter) for its Victorian housing to give you ideas and inspiration on how you would like your restoration to develop.
Get a free estimation. This will give you an idea of how much your restoration will cost even if you decide not to go with professional contractors and do the bulk of it yourself. Websites like Oldhouseweb.com offer signposts for free estimation for windows, plumbing and other services.
Check out architectural salvage sellers. These can help you find random parts to fill in the restoration of your building. For example, www.oldhouseweb.com, has a bank of retailers who sell old cabinets, cupboards, lighting and other features. This can be a cost-effective way of completing the restoration of your building.