You can hire a genealogist, but what fun would that be. That’s like buying a 10,000 piece puzzle (or ikea furniture) and hiring someone to put it together for you. Think of the sleepless nights you can spend rubbing your eyes in front of your computer trying to figure out why your great great aunt’s sister had a different last name (answer: it wasn’t a sister, it was a cousin or boarder). Your kids will appreciate your willingness to endure three straight months of sleep deprived crankiness when you inform them that they absolutely should care that their distant ancestor was the town shochet (“no, come back here right now, i’m talking to you, do you realize our family had the privilege of always having some form of protein in the cholent? what do mean ‘so what’?”)
What you find useful may depend on what part of the world you are interested in. Ancestry[.com] has many databases of all types of historical documents (birth and death records, old censuses, ship manifests, etc). It also allows users to build and share family trees and attach documents from various databases. As you build a family tree, you may find that a distant relative (or relative of a relative) did some work that can fill in sections of your tree, which you can then use to finding more information.
I would read up on the privacy issues for any ancestry building website especially if you will be providing information about living people.