Other posters have already given great tips for questions to ask, so I thought I'd add my overall approach. I assume that you're not specifically asking about small talk, but rather about how to hold conversations with strangers, such as in a party setting, maybe to kill time, maybe to get to know someone (your date?) better.

I am normally an introvert and I am somewhere between bad and okay at small talk because it bores the hell out of me, but I hold my own perfectly fine in conversational settings.

The key for me was to understand that small talk is like kindling, not firewood. It'll get a conversation started, but it's very hard to keep it going with just small talk. If you want an interesting and satisfying conversation that flows (relatively) naturally and where you really get to know someone better, you have to move past small talk quickly.

So I might start with mentions of the weather (common opener), or if they're parents, questions about their kids. However, I don't try to have a conversation about weather. I'm actually rapidly scanning for something substantial to work with. What do you do in bad weather? Good weather? Oh, you play pick-up soccer? Are you a soccer fan? Which club? Do you ever bet on games? Who do you play with? How did you meet them? Oh you're from North Carolina? Ok, can you tell me what the difference is between your barbecue and Texan barbecue? I've been told they're different, but I've never tried it.

That takes... maybe two minutes? And now we can have a conversation where this person spends the next five minutes telling me about how they do their briskets. When they finish, I either end the conversation so that it doesn't die a slow death, or I go back to prospecting for topics.

If the prospecting strategy isn't turning anything up but I get the sense that they're the touchy feely type, I sometimes try intentional vulnerability. "Hey, can I get your opinion on something? I'm trying to figure out what to get a friend for their birthday, but I'm bad at thinking of presents and I'm running out of time."

If I think they're the thoughtful type I might just go straight for something heavyweight like "so in your work, what keeps you up at night?"

If they're just not really responding, you shouldn't try to force it. There are people (and some really smart people) who might have to warm up to you first. If I were a better conversationalist, maybe that wouldn't be necessary, but I'm not, so sometimes the conversation just isn't going to go anywhere, and that's okay.