"Someone came to my home offering to do work on my home...."
This is an all too common way for thieves to scam anyone of any age out of their cash. Be careful of people who portray themselves as "contractors" or "repair persons" and claim to have just done work at a neighbors home down the street.
Before agreeing to any work, make sure you check their references and talk with the "neighbor" that had the work done. Be sure that they have the appropriate permits and insurance. Check to make sure their license is valid and call the Better Business Bureau in the city of their business to check for complaints.
Always have a complete and detailed written contract and plan for payments that will protect you in the event the worker fails to finish the work and disappears. Paying up front for materials and work that isn't completed is risky and an unscrupulous provider may view this as the perfect opportunity to rip you off!
Have a trusted family member or friend review the contract with you. Two sets of eyes and brains are better than one and they may pick up something you missed which could have cost you in the long run.
More crime prevention information can be found here.