I have been doing this for some time. I used to buy peat pots and start the seeds in them. That gets rather expensive because the peat pots are 20-30 cents a piece and to fill it full of soil - is another dime. Some of the seeds wouldn't sprout and you CANNOT reuse soil to start seeds so I would have to throw the empty ones in my garden. There is a better way - and its how commercial growers do it. When you see the six packs - at your home improvement store, you wonder how they got all six seeds to sprout and there weren't ever any empty cells. Most plants are started in plug trays. They are a tray with small pots for starting seedling, The come in 72 cells, 128, 218, or 512 plugs for really small plants and seeds.
Here are some pics of my plug trays. These are 128 cells which i am preparing for tomato seeds.