Many new gardeners ask me about growing herbs from seeds and I tell them I usually get mine from the stores. They are a good investment. A small pot of nicely grown herb costs a few dollars but with proper care, it can last for years.
That said, it's not that you can't grow them from seeds. It's just that some can be quite challenging to grow especially in our climate. They're also prone to disease (they're delicious, thay's why!) and come under attack by pests during the early stages of growth.
I like to buy the tiny pots of oregano, thyme and sage from the chiller section of the supermarket and grow them in a larger pot at home. I like that they are organic but you have to be careful to let them acclimatise slowly in your home. They'll die quickly if you place them under the sun. Remember they used to live in a chiller!
Lately I don't see them anymore in the supermarkets, so I got the larger pots from the nursery instead. They're usually lush and attractive, but also doused with fertiliser and chemicals. I won't use the leaves for cooking for the next few weeks until I'm very sure they're safe.
Here is an oregano that I bought recently. Within a month, it has grown so much that it's trailing all over. The great thing about herbs is that, the more you cut, the faster new leaves will grow.
I like to pound oregano with garlic, salt and rosemary together as a rub for provencal roast chicken. Trust me, it's good.