Answer: Be elected for a first term, the second term will follow.
It turns out it’s pretty likely that a president will be elected to a second term. If we examine all previous Presidential Elections, we will see 8 presidents who failed to get reelected:
|Benjamin Harrison||Failed to get reelected in 1892|
|George H. W. Bush||Failed to get reelected in 1992|
|Herbert Hoover||Failed to get reelected in 1932|
|Jimmy Carter||Failed to get reelected in 1980|
|John Quincy Adams||Failed to get reelected in 1828|
|Theodore Roosevelt||Failed to get reelected in 1912|
|William Henry Harrison||Failed to get elected in 1836|
|William Howard Taft||Failed to get reelected in 1912|
On the other hand, if we look at all presidents with 2 or more terms, we only see a few Presidents who have failed to get elected. Some of these, like Andrew Jackson, failed to get elected initially but were then able to get 2 terms in office. Grover Cleveland had non consecutive terms in office. In total, there were 16 presidents who had a second term.
|Andrew Jackson||Failed to get elected in 1824, was elected in 1828 and 1832|
|Dwight D. Eisenhower|
|Franklin D. Roosevelt|
|George W. Bush|
|Grover Cleveland||Failed to get reelected in 1888 (was pres in 1884 and 1892)|
|James Monroe||Failed to get elected in 1808, was elected in 1816 and 1820|
|Richard Nixon||Failed to get elected in 1960|
|Thomas Jefferson||Failed to get elected in 1796|
|Ulysses S. Grant|
Franklin Delano Roosevelt ran for, and won, a 3rd term in 1940 using the idea that one should "not change horses in midstream." He did not need to do that since it seems people stick with what they are comfortable with.
Note: If I made a mistake anywhere let me know so I can correct it. The data was retrieved from Wikipedia.