1) Do not wing it. Avoid any mishaps such as stuttering or clamming up by writing down your thoughts on paper before all eyes are on you.
2) Plan early. Get this task out of the way so as to avoid stress and scrambling at the last minute to put your toast together.
3) Make it heartfelt. Not only will your toast be caught on video, but some guests will keep your words in the hearts forever. For these very reasons, be genuine in your sentiments.
4) Keep it short. Simple put, guests do not want to be sitting at their tables all night listening to toasters ramble on and on. A couple of minutes should work just fine.
5) Practice. Rehearse your toast in front of a couple of friends and ask for their critique. If you rather wait until the big day to share your toast, practice in front of the mirror to help gain confidence and to ensure that your words flow smoothly.
6) Toast before drinking. You want your toast to be remembered for the sentimental value, not your inebriated demeanor.
I hope that these tips give you a good starting point on perfecting your toast. Best of luck!