Companion planting is something to consider when planting in your raised vegetable garden beds. Companion herbs and companion vegetables help in the control of insects and will improve the health of the garden.
For instance some companion plants for your tomatoes are onions, carrots, and parsley while cabbage and cauliflower need to be kept away. Be sure to rotate your vegetables every year, if you planted tomatoes in the green bed last year plant them into the red bed this year.
Another approach is to use concrete blocks, although less aesthetically pleasing, they are inexpensive to source and easy to use. On the market are also prefab raised garden bed solutions which are made from long lasting polyethylene that is UV stabilized and food grade so it will not leach undesirable chemicals into the soil or deteriorate in the elements.
Lastly, connect your anchors using a heavy-duty string or twine, creating a grid-like pattern of planting squares. You can see an example of the results of this process in my garden bed here: Square Foot Planting Squares.