Rule no 1. The better the weather, the better the experience.
Rule no 2. Keep your hair down to get the famous beach look without surfing, swimming or using any of those expensive sea salt hair products.
...or just use your imagination.
Rule no 4. Take a sister with you...
...so that she can drive...
...and you can relax and enjoy the scenery.
Rule no 6. Wear something else than shorts if your legs are not as ready for the summer as your sister's.
Rule no 7. Come up with a destination so that you don't just have to drive around aimlessly. Someone living on an island is a good visiting point as you wouldn't get there with a car anyway. Especially if they have just gotten a puppy.
Rule no 8. Keep your eye on the puppy when getting back on the boat. She may wanna join and that can result in a wet puppy.
Rule no 9. Come up with a versatile route so that you can see both sailboats...
Rule no 11. Be careful when fueling, it's feels nasty to get petrol on you!
The final rule. Jumping on the wharf is not advised as there's a bigger risk of an accident than on dry land. But that is exactly why you should do that.