Even before they arrive at the ranch, we know that George expects trouble. In addition to referring to all the times Lennie has gotten into trouble, George also insists that Lennie memorize the place they are spending the night with the instruction that if something happens, this is where Lennie should go.

When the two arrive at the ranch, they soon meet Curley's wife. George makes sure to tell Lennie that he is to stay away from her, that she is trouble. George recalls a previous instance that got the two men run out of town: Lennie thought a girl's dress was pretty, so he wanted to touch it. When he did, the girl cried foul and George and Lennie were forced to flee.

When Lennie meets Curley's wife, her beauty flirting attract him, causing George to warn Lennie to keep clear of her. This exchange foreshadows her murder.

George remarks that he continually has to get Lennie out of trouble. What things does he say to Lennie that lead one to believe he expects trouble? Does it seem likely or unlikely that this new job will turn out differently for the two of them?

Well, about half of what he says to Lennie (literally) indicates that he expects trouble. His first two comments are about Lennie drinking too much and getting sick; Lennie can't even drink water right (again, literally). However, it is his comments on Lennie's forgetfulness and the way he calls him a "crazy bastard" that really drive this home.

It seemed possible for a time that the job might be different in a positive way, due to the new friends, but the killings put an end to that.

Greg

It sounds like you want some exact quotes of George insinuating that Lennie has been trouble in the past. George frequently does this in the first chapter. Steinbeck develops their relationship by allowing George to reveal these little tidbits. These tidbits paint George as extremely responsible, but cynical, and abrasive, but committed:

"Think I'd let you carry your own workcard?" (5)

"An' you aint gonna do no bad things like you done in Weed, neither." (6)

"God you're  a lot of trouble" said George "I could get along so easy and so nice if I didn't have you on my tail. I could live so easy and maybe have a girl." (6-7)

Each of these quotes demonstrates a certain ability of George to guilt-trip Lennie. It seems as if these roll right off of Lennie in the beginning of the chapter, but as the chapter moves along, Lennie becomes a little more sensitive, demonstrating he has the capacity to understand the trouble he regularly causes George.