It is really important to portray yourself as someone who is really prim and proper, someone who never goes against the rules. Therefore, obey the rules as often as possible, especially when you know that others are watching.
Be honest, though remember to lie every once in a while. Make sure you do not lie about something big. Instead, lie about small things and make an effort to make it really obvious that you are actually lying. You want others to think that they can tell when you are telling a lie or when you are being honest. Fooling them into thinking this is really important for obvious reasons.
Make yourself comfortable with lying. It can be very tough if you are not used to it, but you need to practice the art and look as natural as possible while lying. Either ask a really good friend to help you out or simply practice lying while standing in front of a mirror. You need to be able to see yourself in order to work on your face expressions.
Try to do extra work and put in an extra effort whenever you can in order to gain the trust of people around you. Remember, trust can get you out of the ugliest of situations.
Always have a back-up plan to escape in case things do not go according to your plan. You do not want to find yourself cornered when others catch on to your original getaway plan.
If you find yourself caught, do not spill everything. Only tell them what they already know. In order to keep yourself from revealing too much, give short answers, carefully filtering out the details.