[X]Research more on Angel and other famous vampires. As much as you don't like the idea of Angel and Buffy getting together, all of the media you've seen tells you that trying to discourage a relationship would only backfire. Instead you'll learn as much as you can in case things go sideways. Learning more in case other strong vampires show up wouldn't hurt either.
[X] Look into Angel's whole "curse business" that Xander doesn't fully believe, ask Giles and Ms Calendar about how curses work in case you run into them in future