You have no restrictions, other than complying with the Laws. The system is for a partnership who will learn and remember it, not one to try to teach over the table to someone you've never met before.
Please explain WHY your choice is the best.
If you'd like to play different methods on different occasions: please answer the poll on the basis of IMPs, dealer at love all, against a good pair; and comment.
Benefits include:
Plus... it's free!