My raised beds are made out of 2 x 4 untreated lumber and held together with a 12" piece of 4 x 4 at each corner.
My raised beds are 4 ft by 8 ft. This is a length I can reach across but still holds a lot of plants. I grew all my veggies in 2 beds like this last year. This year I am adding 2 more beds (the one above and another one) and I'm growing in some containers.
I put cardboard underneath the beds and out several inches on the sides to keep weeds from sneaking in.
Around the outsides I put mulch to walk on, in this case shredded cedar, but I have used dried leaves and commercial bark mulch.
The inside of the bed will be filled with screened compost from Fertile Garden. I get 1/2 yard of compost in my Dad's Ford Ranger, that will fill one of these beds. They sell "Garden Soil" but I have found the veggies grow best in straight compost.
For the containers, I like containers that are at least 1 foot across and deep, any smaller needs too frequent of watering and doesn't have enough room for roots. I like the potting soil you can buy at Fertile Gardens, too, but you only need a bag and not a whole truck load. You can also bring in a 5 gallon bucket and fill it up for cheap! :)