Tom Sawyer is the main character in The Adventures of Tom Sawyer, and his goals shift throughout the book. The difficulty of answering this question is that Tom Sawyer has no over-arching motivation throughout the whole novel. One could argue that what he wants most in the world is adventure, respect, or a good time, but it is difficult to pick out any one of those amorphous feelings as a primary goal.
In some ways, The Adventure’s of Tom Sawyer is a series of vignettes. Tom has many minor goals, such as getting out of painting the fence, marrying Becky, surprising the town by resurfacing at his own funeral, and finding hidden gold. Even while searching for this treasure near the end of the novel, Tom’s goals do not amount to much, claiming that he would use the gold to “buy a new drum, and a sure-‘nough sword, and a red necktie and a bull pup, and get married” (chapter 25).
Tom usually accomplishes his minor goals, but what stands in his way is often his own charm and cleverness. For example, he successful convinces his crush Becky Thatcher to become “engaged” with him only to let it slip that he was once “engaged” before: “Oh Tom! Then I ain’t the first you’ve ever been engaged to!” (chapter 7). Another example of Tom being too clever for his own good is when he successful wins the prize Bible—only to later reveal that he does not know any scripture at all.