This is actually pretty simple. Anyways when you go through a level and collect 50 rings and jump in the giant ring just save the game. Now go through the warp zone and if you fail just exit the game and reload it until you know the warp zone well enough to earn the chaos emerald.

You can actually do this for every achievement. It's pretty much the only way to do Perfect Win and Fast Win without being a God at the game.

I believe that the easiest way to collect the seven Chaos emeralds is to use Rouge the Bat instincs.