Ask for identification and find out how the funds will be used. If you are suspicious call the police. Purchase and install a 180 degree peep hole to safely observe who is at your door. Call the police if you are in doubt. Beware of telemarketing.
Illegal telemarketing is a crime, and fraudulent telemarketers are criminals.
You can't tell by the sound of someones' voice whether or not they are honest. Legitimate companies don't pressure people into sending money immediately. It is illegal for contests or sweepstakes to require payment to enter or claim a prize. Legitimate marketers are willing to send written information about the products or services they're selling. If you give money to a fraudulent telemarketer that money is usually gone forever.