I always get excited when someone says they want to have a place in their garden for growing veggies. I know they're on the right path to good health, right livelihood, and being a good land steward, not to mention a happier person and nicer to be around, which helps everyone.
Raised Beds make it SO much easier and for most, the more organized approach it encourages helps to simplify the process and minimize the time necessary to maintain it.
There are so many variables in terms of shapes and materials, getting a kit or building your own, how high, etc... Squares? Keyholes?...
Shepherd Ogden offers two good points of advice that I've seen to be true in every case:
"Whatever the size and shape, your garden site should be as close to the house -particularly the kitchen- as possible"
-and-
"Make the beds modular. That is, even if they are not exactly the same size, try to keep at least one dimension (usually the width) the same."
The closeness to the kitchen is obvious and the befits go well beyond convenience. The trick is the compost location. I like to have the main path from the kitchen/house be the widest, go directly between all the beds and terminate at a hose bibb next to the compost, preferably in some shade with a place to sit.
But the dimension... what to use? For many, many years I've been using 4'. This is the width at which almost anyone can reach into the center of the bed without stepping into it. I've had 5' beds and they do offer more space (and cooler soil -more on that in a bit) but unless you're extremely mindful and strong willed, most will end up stepping in the bed.
I find myself in the wonderful, yet embarrassing, situation of needing to build new beds. Wonderful: yes! Building the garden is sometimes more fun than working it for me. Embarrassing?: Yup. You see, I moved onto a new piece of land TWO YEARS ago and I, a gardenaholic, if there is such a thing, haven't built a raised bed yet. Part of the hold up is: no fences and lots of rabbits. -and other priorities... but I'm determined to get some beds in and get back to the proper "rhythms of growth" that have accompanied me for decades and help me to relax, keep my sanity, so to speak. So they've been on my mind. flapper items to wear of the wedding
... and I'm actually considering 5' beds. The new garden space, you see, gets HOT. This year we've had a slew of days at 110 degrees and one at 113. This is normal in this climate zone. Rather than wondering about extending the seasons with cold frames and such I'm more concerned about not cooking the plants and being able to apply enough water to keep them hydrated.
-So I'm also lowering the beds: using 2x6 instead of 2x12 -which will help with the costs as well. -But the garden area also can flood. I've seen the pooling in winter, so some elevation is necessary and I want to have an easy system for hoops and row cover. -Maybe even shade cloth!
~Stay tuned as I think I've hit on a solution that will be awesome for years to come.

I've read many times that it's wise to wait when moving to a new garden, to experience the rain, see the drainage, experience the heat, meet the potential garden marauders, and spend time in contemplation, dreaming... using that mental white board to work out the flow, see the Chi, how the mechanics can work, and being open to new concepts in the new plot. ~of course this is all correct and I'm grateful to have had to wait.
Garden On, My Friends!