Ok this is HIGHLY hypocritical of me but: Don't waste your time writing whole new sets of rules when there are a thousand different games to pick from. Sure house rules are fine but leave the writing of new ones to others. You will NEVER get rich or famous writing new rules. If you REALLY want to see your name in print write a GREAT adventure for an existing game! Spend your prep time on your setting or individual adventures
Ok now I admit I wrote my own set of rules but that was because one of my players did ALL the hard part, formating and actually doing the typing plus I have no money and a lot of time on my hands.