Star Wars Prequals: Don't. Prequals never work, as they always violate the established canon. Make episodes 7-9 instead, George.
If you must: Episode I needs these changes just as a start:
1. No one elects a 14 year old queen. Have her inherit at 18, new to the throne, and rewriting the trade federation treaty her regent signed.
2. Make Anakin older. 8 year old falling for 14 year old = creepy, 8 falling for 18 is creepier. Make him at least 14. Or better, 16-17. Also solves the "Too old to train" nonsense. Too old at eight?
3. Jar-Jar needs a major re-write. Coward? Fine. Clumsy? OK. Lazy? Alright. Loose limbed walk with a Jamaican accent? No. Ties into too many racist stereotypes. Try it with a German Bavarian accent, and have him move like Gomer Pyle. Or something.
4. Have Darth Maul escape after killing Qui-gon Jinn. Use him as the emperor's right hand for the entire trilogy (vice Darth Tyrannus aka Count Dooku), until Anakin kills him in Episode III.
5. Anakin scores the lucky shot? No. Give Obi-Wan the fighter and have him do it. Heh... Darth Maul kills Qui-gon in front of Anakin, turns to Anakin, *winks* and leaves... rematch in episode II.