I haven't paid much attention to his policies so some of this is assumption. But here are 4:
- Salvaging the Iran Deal (assuming he supports this)
- Cancelling the exit from the Paris Accords (assuming he supports this)
- Keeping and fixing Obamacare rather than scrapping it, especially since those in favor of scrapping it have no plan to replace it
- Re-establishing normal foreign relations (IOW, stop placating dictators)