Let's do this by example. Say you are toasting firefighters. Your toast might be as follows:
Firefighters risk their lives each day under perilous conditions to save our lives. They are courageous workers whose reward is helping others. To courageous firefighters.
And then the audience would say, "To courageous firefighters" and drink.
Don't stuff to many words after the "To". For example, say you ended with:
To courageous and giving firefighters who risk their lives each and everyday to serve and protect us.
This is not a good ending for a toast. There are too many words after the 'to'. Remember that the audience has to say this back to you. Get a room of 30 people and you will have people not remembering what they are going to say and fumbling over words. Keep the "to" part of a toast short and sweet so that others can easily repeat it.