Daisies are pretty hardy, but it is still wise to have your fresh cut flowers inserted into florist foam. This definitely gives them a longer life span.
If you wish the "hand tied" look, consider making a "mock hand tied" daisy bouquet. Use a straight handled holder instead of the normal slanted and save your cut stems to create the look.
Bouquet holders come in different sizes. Unless I'm making a small tussy mussy (suitable for young girls or flower girls), I tend to use the largest holder. Flowers drink a lot more water than you realize. The larger cage will hold more moisture and won't have to be re-watered as often.
Your bouquet holders should always be thoroughly soak in water that has been treated with fresh flower food. Follow the directions on the label. Using too much won't hurt the flowers, but it will waste product.
Secure your bouquet holder by wedging it in a narrow necked vase that is weighted down with rock or marbles. Realize that the combination of flowers and wet foam is heavy and can topple forward without warning unless you have it weighted.