A friend asked me how I planted my herb pot, so I give you here my stripped down version of Herb Pot 101. I planted mine in January, and it's growing strong. I use the thyme and parsley all the time-for stews, chicken, yadda yadda.
Ditch the plastic-encased herbs from the grocery store. Snip your own herbs for free, as you need them. It's so simple, you'll be disappointed when you bury your last herb and magic sparks don't erupt.
I'm no green thumb. There were herb plants in my past. I either abandoned or killed them all. But here I am, with my own balcony, and it happens to get sun, so I'm going to grow stuff.
With sun, drainage and water, plants will do fine. You're not growing blue ribbon roses here, so go buy yourself some plants and have at it. Start small-one pot-and go from there.
Herb Pot 101
You will need a spot that gets partial to full sun, obviously in a place that doesn't have deathly frost each night. I can't say whether an herb pot would do well in darker or colder conditions, but high school biology makes it clear: Sun is a must.
What you will need for one large herb pot:
1 large pot, at least 16" or so high and with a hole at the bottom
1 saucer to place underneath the pot
 Fill your pot 3/4 of the way with potting soil.
 Take your herb plants out of their boxes, gently massage their roots, and arrange them in the pot (on top of the potting soil).
 When you are happy with your arrangement, fill in the gaps around the plants with more potting soil, leaving an inch of space beneath the pot's edge. Water thoroughly. Done!
Pots come in a variety of materials. Plastic will work fine, though it won't drain as well as terracotta. On the other hand, plastic is lighter and will not dry out the way terracotta will. I chose terracotta simply because it was aesthetically more pleasing.
No need to get fancy with the potting soil. I went with one of the cheaper versions and can't remember the name of it. Any standard nursery store potting soil should be fine.
You can place a layer of gravel at the bottom of your pot to help with drainage and to prevent soil from leaking out. I was told by a helpful nursery employee that potting soil is already made to drain well, so I went without it and was fine.
Three things to consider when selecting herbs for a pot are (1) compatibility, (2) arrangement, and (3) use.
Compatibility: Most herbs can be grown together, with the exception of mint and its relatives (ex. lemon balm). Mint is invasive and can take over its surroundings, so plant mint separately. Certain plants enjoy drier soil (like rosemary), while others prefer moisture. But I haven't read that you can't mix rosemary with moisture-loving herbs, and the health of my plants suggests otherwise.
Arrangement: Imagine how your pot will look once complete. The taller herbs will be in the middle, and the low creepers (ex. creeping thyme) will be on the edges. Read the plant marker or seed packet to see the maximum height for your plants. I don't know if I did mine correctly, but I put rosemary, parsley, and basil all sort of near the middle, then oregano, then my thyme on the outer edges of the pot.
Use: Plant the herbs you will use. This should go without saying, but too many people (ahem) become enamored with the idea of making tea sachets or five course gourmet meals and plant herbs they will never in fact use. Have I ever used my fragrant emon balm? No! How about my mint? No! The herbs I use most often are parsley and thyme, followed by rosemary.
Finally, fertilize your plant once in a while. I bought these pods that are inserted into the soil for a slow release of nutrients. You can buy them from any nursery. A liquid fertilizer would work, too.