Where to start?

Decide the placement of the garden. You want it to be in the sunniest part of your yard.  Boxes can easily be made if you are considering a raised garden.  I have two raised gardens that are 4 feet by 8 feet in size.  I use wood that does not easily rot.  I do not use pressure treated in my garden, although my fence posts around the garden are pressure treated.  I plant my lettuce, spinach, carrots, peppers, herbs, onions, and garlic in raised beds. I also line the walkways with landscape fabric to reduce weeding.

Tomatoes are a whole other story.  Having grown up with a very Italian grandfather. I espalier my tomatoes on stakes by removing the suckers and attaching the vines to the upright stakes and the horizontal stakes.  I don't grow them in my raised beds but beside them.  There are many techniques for growing tomato vines and this is just the way my grandfather did it.

I also do my zucchini and my beans beside my raised beds.