General notes about rules at this game

I am a very lenient game master. Just present me your ideas and we can discuss them. We can also try implementing new rules or ideas and then if it is offsetting game play or game balance, we can change it. I just want the games to be fun to play for everyone. But the more powerfull the player characters are, the more work I need to do as I have to increase the power level of the enemies.  So I would like to keep some balance on the overall power level of characters - if they become too powerfull it just makes my job much harder to make the would fun and challenging to play.