Hey newstart,
yeah, you definitely want to conquer lust and acting out BEFORE you get married. Marriage will not solve the problem. The proof of this is all over this site; There are tons of married people here, struggling just like you and me.
This is because, sadly, they never conquered their lust before they got married. You and I are very lucky that we're working on this stuff now. Don't think to yourself "if only I were married, I wouldn't have this problem". Wrong attitude. It's true that being married is an outlet for this and it will help you, but only if you take care of things now and make sure you go into it healthy...
And yes, 12 steps is the cornerstone, but you should use any and all tools that help.