What's the best way to approach a "sneak peak" before it goes into the actual video?

I'm refering to an 45 second attention grabber/highlights before launching into a 20 minute talking heads video. I've already cut the couple little snipbits that I want in the highlight video, but I'm not sure exactly how to approach it so it's regonizable as something along the lines of "what's ahead." Transitions? Graphics? I don't want it to be over-the-top...I'm probably overthinking this.