New Jersey Gov. Chris Christie (R) came for fundraising and electioneering on behalf of gubernatorial and Senate Republican candidates. Sen. Rand Paul (R-Ky.) and Texas Gov. Rick Perry (R) have become regulars. Yes, suddenly everyone likes to visit Iowa.

Shorthorn cattle are pictured at the headquarters of Trans Ova Genetics in Sioux Center, Iowa, on June 16. (Juliette Michel/Agence France-Presse via Getty Images)

As the candidates and the media flock to the Hawkeye State, it’s important to keep a few things in mind:

1. The polls mean nothing right now. We are 18 months out, and it is often only in the last few weeks or even days before the Iowa caucuses that the race shapes up. Rick Santorum came from behind late in 2012, Mike Huckabee in 2008.

2. Lots of offices and staff catch media attention, but that shouldn’t be confused with on-the-ground support. Mitt Romney had a huge organization in 2008 and lost. Rep. Ron Paul (R-Tex.) was staffed up and didn’t win in 2012. A much better indication of organization will be the candidates’ connections to religious leaders and their flocks and to other well-organized blocs such as home-schoolers. Both were critical for Huckabee in 2008 and for Santorum in 2012.

3. With a very crowded field, you don’t need very much to win. Since the first caucus in 1976, won by President Gerald Ford, only one Republican has won more than 40 percent — George W. Bush.

4. Social conservatives have greater importance in Iowa (and in South Carolina) than in practically any other primary, and certainly than in the GOP electorate as a whole. That means not only abortion, but also marriage, school choice, religious liberty (e.g. Hobby Lobby protection for believers) and lifestyle issues (e.g. drugs, the candidate’s personal faith), take center stage.

5. The only non-Southerner and non-Midwestern candidate to win since 1984 was Rick Santorum. (President George H.W. Bush counts as a Texan.) Iowa “nice” and the ability to connect with voters are critical.

6. Iowa voters expect candidates to camp out there. They complain if they have met a candidate “only” three or four times. Santorum invested the time — to an extent that surprised even many longtime Iowa watchers — and it paid off. A candidate perceived as coasting on national polls or a declared “frontrunner” based on name recognition or money is vulnerable to an upset.

7. You don’t need to win the caucuses. In 1980, George H.W. Bush beat Ronald Reagan, but Reagan won the nomination and the presidency. In 1988, Sen. Bob Dole won and didn’t win the nomination, nor did Huckabee or Santorum in later years. Sometimes a strong second- or third-place finish is more important, as in 2008, when Sen. John McCain (R-Ariz.) came back from the political morgue to tie for third. The expectations game is as important as the winner. In virtually every race, especially with a crowded field, there are multiple “tickets” out of Iowa.

8. Candidates who do very poorly may nevertheless be in trouble. For candidates expected to do well, and especially for those who invest the time and money there, a poor showing is a serious setback. If the candidates’ target audience in the race overall is evangelical Christians, a loss there prompts the question, “If they can’t win in Iowa, where are they going to win?”

9. If you plan on skipping Iowa, then really skip it. In 2008, Rudy Giuliani couldn’t decide whether to play there or avoid it entirely. He wound up competing — but just a little bit — and lost.

10. The Des Moines Register endorsement, like the New Hampshire Union-Leader endorsement, really does matter. A candidate who performs poorly with the editorial board (especially if it is videotaped) is going to have problems.

Oh, and don’t insult farmers.

Jennifer Rubin writes the Right Turn blog for The Post, offering reported opinion from a conservative perspective.