The Stella Natura calendar is perhaps one of the most important items for seed starting. I have used this biodynamic planting calendar for over twenty years, closer to thirty. Some people are perplexed, even confused by the hourly charting of root, flower, leaf, fruit and blackened sections. I intern find it simplifies my life by suggesting the best garden activity for the time. Experimentation is important as it combines with your intuition. This year the first sowing was Saturday, April 15th, a bracketed flower then leaf day. Tomatoes sprout well for me on flower days (blooms lead to fruit) and well, basil, of course, during the leaf time. Channel or finger flats are filled with dampened germinating mix (Moo Start). Popsicle sticks/arts and crafts sticks are my inexpensive markers, typical New England frugal!
Vegetable seeds are from High Mowing (https://www.highmowingseeds.com), flower seeds from Perennial Pleasures (https://perennialpleasures.net), Pinetree Seeds (https://www.superseeds.com), Select Seeds (http://www.selectseeds.com) and Johnny's (http://www.johnnyseeds.com) for a bit of both.