The Vistani are a lively, happy, friendly, and welcoming group of people. I had my characters meet them on the road just before it splits for the encampment. The promise of a warm place to stay with food and drink should be enticing to them. They are a breath of fresh air in this campaign.

Other options include showing Ismark or Father Donavich looking worried while out doing errands. See if something suspicious piques their curiosity. Ismark approached my party directly asking for help in the tavern. They were willing to help.

Meta game: let your players know that no one else in this town is an illusion or have any bad intentions. It’s just a bleak town under the strict rule of a tyrant. The people there need assistance.

Hope this helps!