Save money and get my no-fail recipes for organic seed starting mix and potting mix that you can easily make at home (all without complicated soil amendments and fertilizers).
Stir the mixture with your hands or a trowel until it's thoroughly moistened but not soggy (like a wrung-out sponge). Add as much water as the mixture will absorb.
Fill your seedling pots with the homemade seed starting mix, add seeds, and sprinkle a thin layer of vermiculite over your seeds if they need darkness to germinate.