I live in Massachusetts, where winters can get pretty cold. In order to get as much "summer" time out of my garden, I decided on raised beds (the soil thaws out faster and you can plant earlier). Also, I wanted beds that were rather narrow because I have a bad back. The less of a reach to the veggies (and weeds too), the better. Keep in mind that this was my first garden, and I'm still learning, but I have loved the layout so far!
Initially we decided to put the garden in a different location from the location chosen by the previous owners of our home. We picked a spot out of the shade of nearby trees, where the farthest side of the garden would be the north side (we planned to have the taller plants on the north side).
I decided on an eight-foot square, creating two garden beds with a narrow path between them. Each bed would be 8' by 3' and the path would be 8' by 2'. Here is a sketch of what I had planned:
8 of 4" x 4" posts, 1' in length
10 of 1" x 6" boards, 8' in length
4 of 1" x 6" boards, 3' in length
Landscaping fabric, 8' x 3'
64 of 3" Galvanized Deck Screws
Note: Be sure that the wood is pressure-treated to ensure that it lasts
He started by creating an 8' square, using 4 of the 4" x 4" posts and 4 of the 8' 1" x 6" boards. Using 2 of the galvanized deck screws per joint (you will do this for each joint throughout the assembly), tightly screw the boards to the 4' x 4' posts. He measured for the location for the 4 other 4" x 4" posts, to be placed on the north and south sides. He attached the 4" x 4" posts, and then 2 of the 8' 1" x 6" boards. This created the first layer of the garden beds.
For the second layer, he ran the 4 other 8' 1" x 6" boards from north to south, attaching them to the 4" x 4" posts. To close the beds on the ends, he attached the 4 3' 1" x 6" boards. Lay the landscaping fabric under the path section, and pull it up the inside of the beds to staple it against the inside walls. That's all for building the beds!
Now we of course filled the beds with soil, and we bought a few bags of river rocks from Lowe's to fill the path between the beds. I would recommend laying landscaping fabric under the path when building the beds. This would help avoid grass and weeds from growing in the path. We did not think of this (beginners, grr) unfortunately, and I have to pull plenty of weeds from inside there.
I wish that I took pictures as he put this together, it would be a great help in explaining the process. Hopefully the explanation helps, but if you have questions please feel free to ask!
Here's a picture of the first planting, June 15 of 2010: