Generic advice here, but always have at least a few commercial stories to discuss in depth:
4 Key stories to have in the bank:
1: I normally research in depth one ‘macro’/ wide ranging issue (i.e inflation, crypto regulation, Brexit etc ), and consider effects on clients/the firm.
2. then another topic on something that is tied to the firm’s key practice area in a more niche way (I.e trends in private equity)
3. A key deal or piece of litigation that interests you (I spoke about the GameStop fiasco/retail investors uprising in my last interview).
4. A deal/piece of work that the FIRM itself has worked on that you found interesting-forgot this in my first interview- never again!
Lastly, go over personal strengths and motivations. Scrutinise and create succinct answer for your motivations for why law, why this firm, and reflect on on past experiences and think about what you contributed/learnt from them and why that would make you a good trainee.