for the prequels, just follow the basics of what vader, emperor, yoda, and kenobi said during the original trilogy. Minus what ben first told luke in the first movie, it just screws things up if you try to stick to it. 1. first movie leads up to clone war or at start of clone war. Kenobi is not yet a general but he is introduced to a brash, hotshot pilot named anakin skywalker. Maybe change his last name since ben only mentions his first name and not his last. ben tries to train anakin against the counsels wishes.(this only works if its done right) yoda finds out that anakin is being trained and has no choice but to knight him because of his skills. Anakin and ben win some major victorys which make them into heros. Anakin meets palpatine, palpatine tries to seduce him. Anakin becomes vader, Vader begins to hunt down the jedi while he is still posing as anakin in the temple. Ben and Yoda are the only jedi who find out who is doing all the killing. Ben goes off to fight Vader, Yoda faces Palpy, except they don't use sabers beings of their level of skill don't need lightsabers. Yoda realizes he will not win against Palpy and goes into exile. Ben wins the fight with vader and vader becomes disfigured forever. Palpy finds vader and rushes him to medical, Vader is put into iron lung. Luke is born. Now it is imparative that Luke be the onlly baby we know of. The Sister is the surprise of Jedi. And we can't know that luke is Vaders son, this is the thing that irks me about this particular method of telling these stories. If you don't do the prequels and you just have 4-6, every generation will be just as surprised to find out that vader is the father as the first generation to see it in the theaters. For all they say about Lucas being a master storyteller this is his biggest flaw in his biggest story. He gives it away too soon if you watch the films in order. You need to be surprised at the revalation of vader being lukes father, it just works.
This flaw also shows me that Lucas never had a grand plan set in place for the prequels to begin with. If he did, he would have written things differently.