Def Soul singer Case, whose Open Letter hits stores April 24, has been given a liberty most artists don't get: on-the-job training.

After selling more than a million copies of his Foxy Brown-featured "Touch Me Tease Me" (which first appeared on the soundtrack to "The Nutty Professor"), Case's 1996 self-titled debut flopped.

He was given the proverbial "one hit wonder" tag.

"It never really bothered me," Case, born Case Woodard, said with a smile. "I love to be the underdog. When people were saying that, I kinda liked that, because I knew what I had up my sleeve."

Case's bag of tricks included a new, smoother musical direction (the first time out, he sang over many hip-hop flavored loops) and future hits, such as the nuptial anthem "Happily Ever After," which he was writing for his second LP, 1999's Personal Conversation.

"I was the first to get signed to Def Soul," Case said of the Def Jam subsidiary whose roster includes Sisqó, Musiq Soulchild and Kelly Price. "That's why my relationship with them is different. As they messed up, I messed up. We grew together. Now I'm at the space where I wanna be, as far as the music that I'm doing, and they're where they supposed to be, as far as the business side of it."

On his latest project, Case's comfort level was the highest it's been.

"[The first album] wasn't me at all," said Case, who grew up in Brooklyn and Mount Vernon, New York. "I had my vision of what I wanted to do, then I had this person's vision, and this person's vision. What happens is, you end up losing what you're trying to do. The second album, I had a little bit of that, but not as much. That's why I look at this as my first album. Def Jam literally gave me the money and said, 'Don't come back till you're finished.' When it goes like that, whether the album goes good or bad, you have nobody to blame."

Just as his second LP does, Open Letter finds Case addressing the people he's known most intimately. "I didn't really have a game plan going into this album," he said. "I had the title of the album maybe four or five months before we started. I wanted it to be a whole bunch of letters to specific people. Instead of mailing the letters and mailing them, I put 'em on the CD, so everybody could hear them. It wasn't bashing nobody like, 'I'ma get you.' It was just like you're in a relationship and something might happen, and you might not [say] everything you want to say."

On "Love of My Life," Case sings about the one that got away because of not being able to communicate. "It was this girl I was dealing with, you could tell she liked me and wanted to get with me," said the singer, who credits fellow Mount Vernon native, Al B. Sure, for helping him develop his songwriting and music arranging skills. "I was mature enough to handle it then, but it was just something about that situation. Neither one of us knew how to move on it. I liked her and wanted to get with her, but I was scared to say the wrong things. She was scared. It stayed there until we drifted apart."

Case, who used to date Mary J. Blige, is seeing his heartache pay dividends as the album's first single, "Missing You," is garnering heavy spins on the radio. His second single, "Not Your Friend" (whose video will be shot in Los Angeles on April 6 and 7) is a little livelier and more uptempo. The cut finds his girlfriend's girlfriend trying to have an affair.

Tim & Bob, who contributed five tracks to the album, produced both of those tracks. Jimmy Jam & Terry Lewis and the Gap Band's Charlie Wilson also help out; Case is so close to "Uncle Charlie" that he has Lil Gapper tattooed on his arm, signifying his honorary membership in the group.

Case will promote his album with a tour starting April 8 in Austin, Texas, and winding up in San Diego on June 2.

Case tour dates, according to his publicist: