Choose a site in full sun. On weed free soil, cultivate the soil to a depth of not more than 1 inch. Before sowing the wildflower seeds, rake the soil to form shallow grooves. To ensure even distribution of seed, mix with four times its volume of sand or vermiculite and broadcast by hand. Then rake the seed lightly into the soil and tamp it for good soil contact. If rains don't come, water to keep the soil moist and continue watering through bloom time.
For seeds that need Cold Moist Stratification (CMS)
Seeds germinate after a period of cold moist stratification. Please note: You do not need to stratify if you are fall planting. Mix seeds with equal amounts or more of damp sand, vermiculite, or other sterile media (moist—but not so wet that water will squeeze out of a handful). Silica sand or vermiculite work well. Place mixture in a labeled, sealed plastic bag and store in a refrigerator (33–38°F). Two months of this cold storage before planting is normally required to break the dormancy of these seeds, one month may work for many species if time is a constraint. Some seeds may sprout in the storage bag if moist stratified too long. If sprouting occurs, plant immediately. Another method of breaking dormancy for species requiring moist stratification is to sow seeds outdoors in the fall so they may overwinter.
Seed Saving for the Organic Gardener by 
The Complete Idiot's Guide to Seed Saving and Starting by 
