I talked to both heroes to get the luck boosts, I gave the guy money for the jet ski, I gave 5 coins to the bald guy, and inside the lottery house I only talked to people who were sure I was going to win (both clowns, the lady with the crystal ball) and the guy with the lucky smoke. I also read the "live,love,luck" sign. I talked to the girl who asked if I was going to buy a ticket, but I don't know if that was important. I didn't talk to anyone else. I used the fortune boost, then remembered the guy at the bottom who tells you about the lottery and realized I hadn't talked to him yet, so I left and did that with the fortune boost already applied.
Then I saved before buying my ticket. Every time I got the wrong number I reloaded and bought my ticket again. I got the right number on about the 5th try, so either I did enough to get the ticket in a few tries or I got really lucky.
I had saved as soon as I came in Deckersville, and on this attempt I forgot to talk to the guy in the inn until after I bought my ticket, but since the number doesn't change once you enter the town, I already knew what it was. I don't kno if that helped or not.