yes, i do believe that your toast should come from your heart, but where do you begin?
I own an entertainment company and i have heard the most delightful toasts. What is your relationship with your sister? Tell a short story about how he came in to the family and how your sisiter was "giddy"..... and how you knew he would be the right one for her.... And course, welcome him into your family as a brother. Offering your love and support is always welcomed in a toast... add sincerity and a bit of humor and you have all the elements of a toast to remember!
one toast is really great.. and easy.. make a lot of keys and hand them out to various men in the room. Tell your sister that it's' time that she collect keys from all the boys now that her "bachelorette"hood is over... it is so funny when the men come up to give your sister back the keys! And your new brother-in-law will have confirmation that he is now the only one!
best of luck, M.
good luck! M.