Hey!! That's a good question and curious to see what other user keep in mind for their prompts and what they use/don't use.
I've found it useful to give AI its guardrails in the custom instructions section aside from the role it should keep in mind which works in conjunction with the guidelines anyway. This helps keep the prompt a bit more concise and focused on the task; I'd also recommend using a few examples to help with consistency.
Of course, still looking forward to other's thoughts and experience!