what can greasers and soc's do to live in peace

There are probably multiple things that the Greasers and Socs could do to live in peace with each other, and different readers will have different solutions. For me, more than anything else, I think a mindset of tolerance would go a long way to help allow the Greasers and Socs to coexist with each other. There's a bumper sticker that conveys this concept. It says the word "tolerance," and each letter is the symbol of one religion or another. I'm not saying that the Greasers and Socs are religious, but they do have their differences. In their opinion, those differences are worth fighting over; however, if the two gangs learned to tolerate those differences, their warring would likely end very quickly.  
The other thing that both gangs could do is take Cherry's words to heart. 

Cherry no longer looked sick, only sad. "I'll bet you think the Socs have it made. The rich kids, the West-side Socs. I'll tell you something, Ponyboy, and it may come as a surprise. We have troubles you've never even heard of. You want to know something?" She looked me straight in the eye. "Things are rough all over."
"I believe you," I said. "We'd better get back out there with the popcorn or Two Bit'll think I ran off with his money."

Cherry points out to Ponyboy that the Socs have problems just like the Greasers. The problems might be different, but they are problems that cause strife and heartache nonetheless. If the Greasers and Socs could start seeing themselves as more alike rather than different, then their attitudes toward each other would be more supportive. They might never be friends, but they wouldn't be enemies.  
Ponyboy learns this fact in Chapter 7. Near the chapter's conclusion, Randy comes to talk to Ponyboy. Randy wants to understand how and why Johnny and Ponyboy saved the kids in the church. Randy simply can't understand why a Greaser would do such a thing. Ponyboy responds by telling Randy that being a Greaser had nothing to do with it. Randy then admits to Pony that he is having a hard time dealing with Bob's death and the pointlessness of their gang war. He's sick and tired of it and the meaningless class distinctions.  

"And tonight... people get hurt in rumbles, maybe killed. I'm sick of it because it doesn't do any good. You can't win, you know that, don't you?" And when I remained silent he went on: "You can't win, even if you whip us. You'll still be where you were before—at the bottom. And we'll still be the lucky ones with all the breaks. So it doesn't do any good, the fighting and the killing. It doesn't prove a thing. We'll forget it if you win, or if you don't. Greasers will still be greasers and Socs will still be Socs."

The conversation gives Ponyboy concrete evidence of how things are rough all over. He has now seen a Soc struggling with the same thoughts that Ponyboy has been struggling with. When a fellow Greaser asks Ponyboy about that Soc (Randy), Ponyboy points out that it wasn't a Soc. It was just another guy. Ponyboy knows they are different, and they aren't likely to be friends; however, through mutual understanding of each other, they are no longer enemies.  




"He ain't a Soc," I said, "he's just a guy. He just wanted to talk."