Presenting a speech at your brother’s wedding is not unique but the honor normally falls to the best man. It can be a nice touch though. As with all speeches, introduce yourself, guests need to know that you have an important part in the wedding.
Tell childhood stories about your brother for example how he stole your makeup to experiment or sneaked out until the early hours without getting caught (unlike you). Make sure the stories are interesting, don’t bore the guests and make sure they understand – don’t use closed jokes that will split the audience.
Do not to step into best man territory, you don’t want to sound repetitive plus nobody knows your sister like you do so keep it relevant.
If you’re feeling a little nervous about speaking, you could introduce some pictures, this breaks the ice and suitably (but not overly so) embarrasses your brother, just be careful he doesn’t do the same on your wedding day!
Talk a little about your new brother in law, he’s already been welcomed into the family so don’t repeat what has already been said. Just remember to stay relaxed, it’s not a race pace your speech and speak clearly, have a glass of water handy for that dry throat or mouth.
Make eye contact with all the guests; use your arms and look as natural as possible. If the guests feel at ease then so will you. Also don’t be afraid to crack a joke but be original.
All the best and enjoy your brothers big day, saving the drinking until after the speech!