I grow somewhere around 30 varieties in my garden. Most are started from seed planted in the garden where it will grow. Tomatoes and peppers I buy nursery plants. Onions from sets, plants or seed.
One thing to watch is that the new seedlings don't get devoured by bugs, snails, slugs or birds.
Yes, good advice to read the seed packet for tips on the culture of each variety. You can also do some research online on the culture of varieties. Growing a garden is very rewarding. Good Luck!
Gardening at 5000 feet elevation, zone 4/5 Northern Utah, Frost free from May 25 to September 8 +/-