In the many years I've been doing this, it's always been my opinion that ADR is one of the much more complicated post elements you will work on. The suggestions above will get you everything you need, but remember this: even professional actors have a difficult time re-recording their dialog. It might take you a bit of time to get an actor without ADR experience to be able to re-enact the scene.
From a directors perspective, you need to get the actor back into the element, back to the scene. You need to have them watch the clip, many, many times and rehearse it out-loud as you preview it. It may take a few attempts to get the actor back into the element, when you recorded the scene the actor was involved in that moment. They were immersed in sets, environment, props, costumes and were truly the character they were portraying. It might take a few tries, but the actor can easily return to that moment, and sometimes, perform the scene even more brilliantly with a slightly different take or inflection.
The other thing key to ADR is being able to recapture the sounds of the environment. Most professional films actually record static noise for several minutes from the actual location or set to be able to do ADR effectively. If you don't use actual or re produced location sound your environment will fall flat and it will immediately take your audience out of the scene. If you don't have a good track of actual location or set noise, I recommend ADR on the entire scene, otherwise it will cut really odd...