Starman Jones by Robert A. Heinlein

I think Heinlein chose to tell this story just for the title. He had a hankering to tell the story of a Martian named "Smith" and I think he just had to accompany it with a Spaceman named, "Jones". Max is a dirt-poor farmer in the Midwest whose father passed away, leaving him to keep the farm going for himself and his step mother. When his stepmother gets married to a ne'er do well named Montgomery (Heinlein re-uses this name for one of his villains in Time Enough for Love), Max decides to run away from home and join the Space Force. His uncle, Chet, was an astrogator, and he hopes that he's been named a "legacy" and will be allowed to join the Guild.

On his way he meets a hobo named Sam, who shares his fire and a meal. Sam steals Max's uncle's reference books while Max is sleeping and leaves him behind. When Max gets to the big city, and approaches the Guild about membership, Sam has already been there, claiming to be Max, but disappeared when the people there wanted to get his fingerprints to confirm his ID. Max is disappointed when he finds out that Chet died without naming him heir, and turns down their offer of sponsorship to a groundhog type of guild, leaving in a bit of a snit, but with a bit of cash in hand as a return of the "deposit" on his uncle's books.

Outside, he encounters Sam again, and after some initial hostility on Max's part, they decide to let bygones be bygones. Sam comes up with a plan to get them both into space as crewmen on a ship, by falsifying their identities. Amazingly, the ploy works, and the two of them end up as crewmen on a cruise liner for rich folks traveling to a pleasure world on vacation.

Lots of great adventure here, and a number of little morality plays in the course of the plot's unfolding.

One quote for all you bibliophiles:

"The library book had been burning a hole in his rucksack...the book had to be returned. Vagrancy in the eyes of the law had not worried him, nor trespass, nor impersonating a licensed teamster - but filching a book was a sin."