Making the most out of Booming Blade?

I'm a level 3 Blade Singer and I took Booming Blade after reading some recommendations. How do I make the most out of it?

If I'm attacking with Booming Blade (BB), what's the best way to get enemies to move, thereby causing the extra damage? Enemies almost never want to move to provoke opportunity attacks, so they generally stand still during melee fights. Sure, I can use BB for an attack of opportunity if an enemy runs past me, which is nice. But that's not something that happens frequently.

Can someone lay out some strategies for getting the most out of BB? I took the cantrip, but I'm kind of puzzled by its (seeming) lack of usefulness. How do I best use BB?

(I will add that at level 3, I'm not doing much melee fighting yet. I'm playing mostly as a typical back line wizard. But I want to get in and use my scimitar once in a while!)

Thanks.