Grabbing openings and memorable, Call-to-Action closings. Two elements I always recommend speakers give special attention to, when planning their talks.
The way you begin sets the stage, tone, energy and the audiences' expectations ad motivation to keep listening.
The end is your opportunity to invite them to do something with what you've just shared. Here's a super fun discussion in Prof. Angela Duckworth (Grit) and Stephen Dubner (Freakonomics)'s trademark playful-and-informative conversational style, https://freakonomics.com/podcast/nsq-impressions/ analyzing Nobel Laureate in Economics Prof. Daniel Kahneman "Peak-End Theory", with plenty of references to remembering beginnings, ends and also - significant peaks even if they are situated in the middle.
Who knew colonoscopy studies (!) could teach us about effective public speaking?!