"I said to him, 'I want you to be the same person, but you have to be more smart because you're going to have a lot of people come to you,'" Soriano said Monday about his advice to the 22-year-old shortstop.
"[I told him] 'Just believe in your father and your mother, and don't forget where you come from and who gives you the money,'" Soriano said. "'Baseball gives you that money. Don't quit because you have the money.' Now is the time he has to work more because you get paid if you're a good player."
The deal could be announced as early as Tuesday. FOX Sports' Ken Rosenthal reported late Monday that Castro's seven-year, $60 million deal would include a $6 million signing bonus with salaries of $5 million for the first two years, and increase to $6 million the next year, then $7 million, $9 million, $10 million and reach $11 million. There is a club option of $16 million or a $1 million buyout.
If Castro wins the Most Valuable Player Award, or finishes first through fifth twice, the final year of the deal and the option year each escalate by $2 million. The deal would cover all four years of arbitration plus at least two free-agent years.
Castro's agent, Paul Kinzer, was at Wrigley Field on Monday to finalize the deal.
Soriano, 36, gave Castro some examples of players who have lost their money by spending unwisely or giving it to so-called "friends." Plus, the veteran gave Castro a little dose of reality. He reminded Castro he'll have to pay his agent, plus pay taxes.
"You get $60 million and it sounds like a lot of money, but you give 40 percent to the United States -- or 50 percent," Soriano said. "It's not $60 [million] -- it's $30 million. You have to be smart.
"[Other people] will say, 'Oh, he signed for $60 million,' but they don't see his family, they don't see he has to take care of himself, save money for the future," Soriano said. "[Those people] don't know that. I hope he knows that he has to be smart and not spend too much money. This is baseball. That may be the only contract you have. You better save money for the future."
Soriano knows a little about large contracts. He received an eight-year, $136 million deal from the Cubs in 2007.
"When I signed my contract, I was 32," Soriano said. "I knew what I wanted. Before, during my years of arbitration, I had a lot of 'friends,' but my agent and my financial guy were always on top of me. They said, 'You got the money, more people will come. Don't be afraid to say no. You didn't have that friend before -- why is the friend now coming?'"
When he signed his first contract, Soriano said he bought a house for his mother. He does not live extravagantly, and hopes Castro remembers his advice once the deal is done.
"I hope he doesn't forget," Soriano said. "I want the best for him. We'll see what happens."