When Structuring a Gambling routine I suggest you keep it short and to the point. Astound them and leave a lasting impression on them. To many try to show too much gambling stuff in one setting. I was one of them. After learning new moves and routines I would just cram them in there. My audiences would be wowed then by going on for too long they would be like "oh that cool".
I stick to 3 things in my gambling demos. A shuffle tracking demo with locator card talk, false dealing (second, Center, Bottom and Greek) and finish with a 3 card monte. It would last 10 min tops if I take it at a very slow pace.
Good balance is key. Be informative, a bit mysterious but don't go to far where you would make your audience feel stupid or come across as a wise ass etc.
I would suggest getting Darwin Ortiz's Strong Magic for theory and structure.