Salad Bar gardens are all the rage and rightly so-they're easy and fun.
Growing them from seed is cheap and pretty simple. First, decide on your greens.
I'd recommend getting a fair amount of leaf lettuce and then adding some of those bitter, peppery fellows like mustard greens, watercress, arugula, endive. Try your luck with some spinach if you like and also some parsley, chives, cilantro and basil a little later in the season when it warms up. I love having a nice, big parsley plant-it's so easy and you can use it almost every day.
It might be easier to control slugs and snails if you grow your tender greens in containers or in a raised box but you can put them in the ground. Make sure the soil has good drainage. Don't go nuts with the fertilizer-if you use any.
You can start thinning (and eating) your salad greens after they grow a few inches. Let them grow between 4 and 6 inches before you truly start harvesting them and then cut them down again to about an inch and let them grow again. You can harvest them a few more times but you can also sow some more seeds at this point to ensure a nice, new tasty harvest. If your leaves start to taste bitter the plant is getting too mature. Have fun!