Summarize:

Working with friends will give you all an advantage.  Remember that your goal will be to share what cards you have with each other.  You will need at least one friend. Too many friends will increase the risk of getting caught. Choosing friends who are trustworthy cheaters will work best.  Selecting someone who isn't in line with your cheating can get you caught.  Only select friends you have known for a long time. Make sure you feel that your friend will agree before asking. Select a signal that will communicate which cards are in each of your hands.  Try to make your signals subtle and repeatable.  Do not choose any signal that might be too obvious to other players outside your friends.  Placement of chips Coughing Tapping the table Blinking Touching ears, eyes, nose, neck, or some other body part. Do not go into a game unpracticed.  Practicing your signals and methods will help you to remain calm and not tip any other players off that you are working together to cheat  Practicing reduces stress, which could get you caught. Work out who is going to raise, fold, call, and when. Keep signals simple and secret. Develop strategies as well and decide when to use them. Working together is certainly cheating.  Do not let new groups of people know that you and your friends know each other.  Playing with familiar people will require you and your accomplices to be extremely subtle.  Don't give any clues or hints that you might be working together. Play as if you don't know what your friends hands are. Avoid playing too well.  Make some mistakes to throw other players off.
Gather a friend or friends. Select friends you can trust. Decide your communications. Practice with your friends. Keep your team work a secret.