Democratic presidential candidates appear at Wednesday night's debate in Miami. (Drew Angerer/Getty Images)
Opinion writer

Wednesday’s lively Democratic debate contains some lessons for Thursday’s participants. The 10 contenders who will take the stage Thursday night had a chance to see what worked and what didn’t, as well as what approach the moderators are taking.

For starters, the candidates had better be ready to answer a whole lot of policy questions on Thursday. To their credit, the NBC/MSNBC/Telemundo moderators avoided silly questions, stuck to substance and generally controlled the proceedings while allowing just a few battles to break out. (Special kudos to Lester Holt and Rachel Maddow, who were firm, succinct and low-key.) On Thursday, if a candidate entirely departs from the question, he or she is likely to get called out. If a candidate has a fuzzy position on health care, he or she should be prepared to be pressed. Night two promises to be another no-nonsense affair.

Second, Sens. Kamala D. Harris (D-Calif.) and Kirsten Gillibrand (D-N.Y.) might want to interrupt the male candidates if they start doing the same. On Wednesday, the female candidates seemed hesitant to interject, perhaps out of fear of appearing too “pushy.” Nonsense. Female candidates should dive right in — and show that when President Trump pulls that sort of stuff in the general election, they will be ready to go toe-to-toe.

Third, if asked a yes-or-no question, candidates don’t have to answer yes or no. (For or against an Afghanistan pullout? Actually, we need to shift to a small counter-terrorism force.) The candidate who wins will have to live with emphatic, unqualified responses. If candidates really think they can defend taking private insurance away from people who like it, fine. However, they should understand that such a scheme loses support when explained to voters. A candidate might want to think carefully whether Medicare-for-all is the end goal or the immediate, next step. Remember: Don’t make the perfect the enemy of the good.

Candidates on Thursday might also want to prepare for topics that were not raised on Wednesday — trade/tariffs, the debt, Supreme Court packing, legal immigration, voting rights, Venezuela, Israel — on the theory that moderators are not going to ask exactly the same questions two nights in a row.

On Wednesday night, we saw how center-left candidates can more than hold their own against ideological purists. On free college tuition, Sen. Amy Klobuchar (D-Minn.) remarked without naming names, “I do get concerned about paying for college for rich kids.” On the debate over the public option vs. Medicare-for-all, Klobuchar was asked why she favored an “incremental” — a loaded word for Democrats — approach. “Well, I think it’s a bold approach. It’s something that Barack Obama wanted to do when we were working on the Affordable Care Act. And that is a public option,” she said. “I am just simply concerned about kicking half of America off of their health insurance in four years, which is exactly what this bill says. ... There is a much bigger issue in addition to that, and that is pharmaceuticals.” Bingo! (In general, I was struck that aside from Sen. Elizabeth Warren and New York Mayor Bill de Blasio, there was plenty of evidence that moderation is alive and well in the party; eight of 10 candidates did not favor eliminating private insurance.)

Finally, limber up, listen to some relaxing music or do some yoga. Candidates have to look comfortable on stage. No nervous tics, no distracting hand motions. Remember to blink. (At times, one or another contender on Wednesday had the “deer in the headlights” look.) And one more thing: The real audience is at home and would appreciate a conversational, calm tone punctuated by some theatrical moments. You don’t have to scream the entire time.

Read more:

Jennifer Rubin: The first debate — who won, who lost and what matters

Stephen Stromberg: Democrats can do better than Warrenism

Ed Rogers: Ranking the Democrats’ debate performances

Erik Wemple: Why not let the Democrats actually debate?

Ann Telnaes: Live sketches of the first Democratic debates’ big moments

E.J. Dionne Jr.: The first debate showed Democrats are far more in consensus than at odds