Good for Rick Perry.

After a fairly disastrous first go at the White House, he's gearing up for a second try. Over the weekend, he told NBC News' Kasie Hunt: "I was not prepared properly." In 2012, he told CNN that the "idea you can just stroll in there and be in the mix and be successful, I think is a bit of a stretch. But, anyway, you live and learn."

That's a bit of an understatement. The last time around, Perry parachuted into the Republican primary right after the Iowa straw poll, effectively landing on the winner: Rep. Michele Bachmann. She may have been the shortest-lived front-runner ever.

Things only went downhill from there. His recovery from back surgery clearly played a role -- he was on pain medication and had trouble sleeping -- but even so, he was a hot mess. He campaigned as if he was running for the job of president of Texas -- and that's when things were going well.

"It's three agencies of government when I get there that are gone -- Commerce, Education and the, um, what's the third one there? Let's see. Oh five -- Commerce, Education and the um, um," Perry rambled during a primary debate.

He's lucky he's not a horse, because they shoot them after stumbles like that.

I don't say good for Perry because I'm endorsing him; I say good for him because he's doing what he should have done the first time: his homework.

This is my biggest gripe about some of the GOP candidates in recent years. They don't think they have to do their homework, perhaps because they aren't so much running for president as running for greater celebrity.

Consider Herman Cain. I love listening to him, and so do a lot of conservatives. He's smart enough to be president. But he simply didn't do his homework, and he acted like that was something to be proud of, as when he of bragged about not knowing the names of leaders of "small, insignificant states" like Uzbekistan (which he jokingly pronounced "Ubeki-beki-beki-beki-stan- stan").

The one thing you cannot buy in politics is charisma. If you could, Mitt Romney would have bought a pallet of it at Costco and he'd probably be president now. Cain and Perry had the charisma, the natural political talent, and they squandered it by thinking all they needed was the sizzle without the steak.

I have similar worries about Ben Carson, who's on a book tour that feels a lot like a walk-through for a presidential run. Carson is amazingly popular on the Republican circuit. He is to older traditional conservatives what Rand Paul is to younger libertarians.

A world-renowned neurosurgeon, devout Christian and an African-American with a rags-to-riches story that beats any and all possible competition, Carson has enormous strengths. (Contrary to a lot of nonsense you hear daily on MSNBC, most of the base of the GOP would love to nominate a conservative black guy.) But while he speaks eloquently and passionately about the importance of doing homework in his own life and for children everywhere, it's not obvious he's taken those lessons to heart when it comes to politics.

In his book, "One Nation: What We Can All Do to Save America's Future," Carson says he'd declined invitations to get into politics in the past. Though he left some wiggle room: "If I felt called by God to officially enter the world of politics, I would certainly not hesitate to do so."

God may be paging Dr. Carson. He recently told the Weekly Standard's Fred Barnes that he's "starting to feel it. Because every place I go, it's unbelievable" how much support there is for him to run.

I have no doubt that's true. But most of the audiences he talks to are already in love with him. You can skate by with a lot of platitudes about common sense and the evils of political correctness (all of which I agree with) when speaking to an audience of your biggest fans. Perry learned that the hard way when he encountered audiences that didn't care that much about the Lone Star State.

Politics, particularly presidential politics, has to be about persuading people who disagree with you, not just telling those you had at "hello" what they came to hear. Maybe Carson is truly ready for a presidential run. If he is, he'd be very hard to beat.