When writing guidelines for a shop I appreciate use of positive language. Statements such as,"This shop requires precise timing." or "Payment will be made based on your submission of an itemized receipt." communicate shopping expectations. Instructions stating negative expectations lead to an increased chance of a negative outcome.
As a teacher I found keeping the instructions brief led to the greatest success. Repeating the same information is likely to lead to a reader skimming over information as added statements become redundant.
When I read clear, concise, brief instructions I can best become a successful shopper.