be nice, listen, smile/laugh when appropriate. in my experience, first date conversations are usually about lighter topics like hobbies, family, work, school, childhood, etc. Talk about that stuff and try to relax. conversation should flow naturally, just like if you were talking to anyone else you know, so don’t barrage him with questions or stay totally quiet, and take turns.
also remember that he might very well be nervous too (especially if he hasnt dated much yet and is more yeshivish), so just accept that there might be some awkward silence. Gam zeh yaavor…
if you can still stand him after 2 hours or so, it’s a good sign. hatzlocha!