Home maintenance first, cleaning, minor repairs.
Replacing any damage second, roof, windows, doors, sidewalks and siding.
Kitchens and baths, then exterior mods to make it maintenance free, decks and patios are the most common "cost effective" DIY projects.
Nothing adds value though, like adding square footage in living space. Sometimes even a garage will not add to the value enough to off-set the cost.
Clean it up, fix it up, update kitchens and baths, make things nice outside, then add space.
[URL="http://www.houserepairtalk.com/announcement.php?f=39&a=6"][size=3]The Ten Commandments of House Repair Talk[/size][/URL]
[URL="http://home.bellsouth.net/p/s/community.dll?ep=16&groupid=289528&ck="]Square Eye's home page[/URL]