Bienvenue to Washington, Emmanuel Macron! You’ve got a lot on your plate, and we’re not talking about the jambalaya that’s on the menu for President Donald Trump’s first-ever state dinner that he’s throwing in your honor Tuesday night.

From convincing the president to stay in the Iran nuclear deal and Paris climate accords to making the case that new steel tariffs shouldn’t apply to the European Union and urging continued cooperation in Syria, there’s no shortage of items on your negotiating list.

But how to engage with the man who calls making great deals his “art form” but is more often compared to “negotiating with Jell-O” when it comes to hammering out the details of legislation or treaties? I put that question out to Democrats and Republicans who have had the chance (or duty) to sit across from Trump in negotiations on everything from a budget deal to gun control to see what advice they have for you.

Watch: Doing Nothing Is Doing Something — Trump, Congress and the Use of Force

Here is a summary of the lessons they’ve learned, sometimes the hard way:

1. Be the last to talk to Trump, not the first. Now would be a good time to book your return trip to Washington, if not schedule a follow-up phone call, since one of the primary lessons that Capitol Hill has learned in negotiating with Trump is the importance of being the last to talk to him on any given subject. From health care to taxes to trade and guns, the president has changed his negotiating position often and abruptly, sometimes completely, after a conversation with someone new. Make sure that someone new is you.

On gun control, Democrats believed they may have opened a door to revisiting the Manchin-Toomey background check legislation in March, possibly even with an assault weapons ban attached, after Trump himself suggested combining the two measures in a live televised meeting following the mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida. But hours after that bipartisan meeting with House and Senate leaders, Trump met at the White House with the leadership of the National Rifle Association, which directly opposed both ideas. That night, Chris Cox, the NRA’s executive director, tweeted, “POTUS & VPOTUS support the Second Amendment, support strong due process and don’t want gun control. #NRA #MAGA.”

Trump quickly moved his support to arming teachers and away from gun restrictions. The lesson: He who has the last meeting with the president usually has the last word.

2.Assume Nothing. When Democrats were negotiating with the president over the winter to give Dreamers in the country a path to citizenship, Trump was presented several times with proposals that were exactly what he called for, which he rejected.

And when Trump didn’t care for a separate agreement that House and Senate Republicans presented to him to keep the government open in September 2017, he went for a smaller, easier deal with “Chuck and Nancy,” namely Chuck Schumer and Nancy Pelosi, which left GOP leaders fuming, since they assumed he would never side with Democratic leaders over them. They were just learning that the traditional parameters of Washington negotiations simply don’t hold with this president. Assume nothing.

3. Flattery will get you everywhere, especially if it’s on television. As former Sen. Fritz Hollings used to joke, he and his wife, Peatsy, got along so well because they were both in love with the same man. Leave the same impression in Trump’s mind, and your relationship with him will likely live long and prosper, too.

Look no further than Rep. Mark Meadows, the chairman of the Freedom Caucus, who is also a frequent on-air Trump booster (and lately a James Comey detractor), and you’ll see a man many believe has mastered the art of the on-air appeal to Trump’s ego. Particularly in health care negotiations, Meadows was able to punch above his weight, which many chalk up to his positive relationship with the president.

4. Do not engage on Twitter. Ever. Just as the president is known to appreciate flattery in public, Capitol Hill knows well that disagreements are best kept private if you ever want to negotiate in this town again. Tennessee Sen. Bob Corker can attest to the dangers of tangling with the president in the public square. After the president tweeted in October that Corker “begged” him to endorse his bid for re-election, Corker fired back, “It’s a shame the White House has become an adult day care center. Someone obviously missed their shift this morning.” Weeks later, Trump was still hammering Corker on Twitter to his 51 million followers.

Corker and Trump did eventually mend some fences — but Corker recently told reporters at a Monitor breakfast, “Any Republican senator who hasn’t been conflicted over this presidency is either comatose or is pretty useless in their blindness — and we’ve got some of both.”

That sentiment may be true, but it won’t help Corker when it comes to convincing the president to stay in the Iran deal as the senator would like to do.

5. It’s Not Over Till It’s Over. Remember that line about Jell-O? That was from Sen. Chuck Schumer in January, after negotiations with the White House to avert a government shutdown broke down even as Democrats thought they had a “yes” in hand.

“Negotiating with this White House is like negotiating with Jello-O,” Schumer fumed. “It’s next to impossible.”

And even when it’s over, like the president’s decision last year to withdraw from the Trans-Pacific Partnership, it still may not be over. Trump signaled late last week he may want to get back into the deal after all.

Welcome to America.