I'll try to answer your question as best I can, even though I'm still relatively new here...

What are the 5 most important things in doing Atkins?

1) Follow the rules outlined by Atkins book! (commandments)
2) Do not fall unto temptation
3) Thou shall count carbs
4) Thou shall drink plenty of water
5) Thou shall exercise and not be a couch potato

What are the TOP 5 mistakes when doing Atkins?

1) People try Atkins using their friends "second hand" advice.. oops!
2) People don't know there's carbs in most everything you eat.
3) People don't measure food portions.
4) People don't like to drink water. They try tea, juice, etc. NO, NO, NO!
5) People get cravings and fall of "ye old wagon".. lol

The hardest part about Atkins is following the rules. Read his book and follow it to the letter.

Good luck!