What is the best way to start a wildflower meadow?
Here is a publication that should help you:
Preparation is very important, with removal of weeds paramount.Often complete kill-back with a non-selective herbicide is done, and then repeated as weed seeds germinate again. A soil test would be beneficial as well. Here is our soil testing page, which includes links/videos of how to take a sample, and a list of labs which can complete the testing for you: https://extension.umd.edu/hgic/soils/soil-testing
You should try to use native plants. Ernst Seed Company out of Pennsylvania has a nice selection of seed mixtures which can benefit birds and pollinators : http://www.ernstseed.com/