It was common in history for brides to only use flowers that had positive connotations. If you want to follow tradition- here's the list:

Anemone- Expectation
Baby's Breath- Innocence
Bluebell- Everlasting love
Calla Lily- Magnificent beauty
Carnation- Boldness, love, talent
Chrysanthemum- Wealth, abundance, truth
Daffodil- Regard
Daisy- Loyal love
Delphinium- Swiftness, lightness
Forget-Me-Not- Faithful love
Freesia- Innocence
Gardenia- Purity, joy
Heather- Admiration
Hydrangea- Thank-you
Iris- Faith, wisdom
Lilac- Love's first emotions
Lily- Majesty, truth, honor
Lily of the Valley- Happiness
Magnolia- Love of nature
Orchid- Love, beauty
Pansy- Merriment
Peony- Happy marriage
Primrose- I can't live without you
Ranunculus- Radiant
Rose- Love, joy, beauty
Stephanotis- Marital happiness
Stock- Lasting beauty
Sunflower- Adoration
Sweet Pea- Blissful pleasure
Tulip- Love, passion
Violet- Faithfulness
Zinnia- Lasting affection

If you are a little on the superstitious side, you may want to avoid these flowers:
Christmas rose: Scandal
Fig: Idleness
Foxglove: Insincerity
Larkspur: Infidelity
Lavender: Distrust
Marigold: Grief
Mulberry: I shall not survive you
Raspberry: Remorse
Red carnation: Alas for my poor heart
Red poppy: Consolation
Rhododendron: Danger
Striped carnation: Refusal
Striped pinks: Refusal
White poppy: Sleep
Yellow carnation: Disdain
Yellow chrysanthemum: Slighted Love
Yellow lily: Falsehood
Yellow rose: Jealousy