Unless you live in a frost free zone, you will be planning a vegetable garden most likely for next year.
There are basics to siting any garden
1. Locate the bed where it will be in full sun
2. If possible plan the bed to be about 4 feet wide and as long as you can manage but most people do not make the beds longer than 10 feet to make it easier to get around them.
3. The bed should be accessable from all sides, so not up against a fence.
4. for the best orientation, allign beds north/ south. Second best will be east/west to make the most of the light
5. Make sure you have a water source nearby or plan on installing an irrigation system to make watering easier. I still would plan on putting a hose bib nearby.
6. When you build the bed, Put in a trellis or at least the anchors for a trellis on the North side of the bed. You will plant the tallest plants on the North side and the shortest plants on the south side so the tall plants will not be blocking the light from the shorter plants. Some short plants can be planted between the tall plants if you actually want them to be in the shade.
7. If you ar a beginner gardener, I would go with only one or two beds, but leave space for more as your experience grows.
8. Some plants are more suited to cooler weather and others prefer heat so you would not plant garlic in the middle of summer or watermelon in the dead of winter. If you can plant year round, then you have to plan your planting based on the season.
9. Get Mel Bartholomew's New Square foot garden book. It is a good book for showing you basics like building planter beds, what kind of soil to put in the bed and a primer for each type of plant as well as minimum spacing requirements.
I find that the spacing is too tight for me and I actually space my plants further apart and large plants like eggplant and tomatoes take up a lot of space in the garden beds so I put them in containers around the beds or in other places in the yard where they can spread out more and use the garden beds for smaller plants to maximize the space. I would also keep herbs and most of the perennial plants outside the garden bed. Herbs take well to pots and are best close to the kitchen where they will be handy and available, perennial plants like asparagus and rosemary can go somewhere in the yard. It is easier to work the garden beds if you don't have to work around long term plants.
https://www.amazon.com/Square-Foot-Garde ... 1591865484
If you want to conserve water and you plant mostly smaller plants, consider a keyhole garden. It is an economical design since the material can be made out of whatever is readily available to you and it comes with its' own compost bin. And you can build multiple keyhole gardens. The maximum recommended diameter for a keyhole garden is 6 ft. The frame is good to build in if you want to use it for shade in summer and also if you want to use it for a trellis.
10. In your garden design, plan a place for the compost pile. It will be a place to put the trimmings and waste from the garden and recycle it back to feed the soil.
11. Take your time, it is a lot of work to put it in and work out what will grow best for you. You also need to plan on spending at least 30 minutes to an hour every day in the garden especially if you plan on hand watering and you will need to get used to the gardener's main job of maintenance which will be weeding and scouting for pests. If you make the garden too big, you won't be able to manage it well. Until you figure out the best place to plant things it is better to master a few
12. Start with beginner plants. Lettuce, kale, radish, herbs are pretty easy to grow ad harvest in a short time. Lettuce and kale grow better in the cooler months of the year.
Tomatoes are people's favorites but they are not the best beginner plants. They are large, heavy feeders and have a lot of diseases and pests that you have to stay on top of. They will grow best in the warmer months.
Cool season crops: Leafy greens, lettuce, kale, swiss chard, spinach, carrots, beets, radish, broccoli, Brussel's sprouts, turnips, peas, onions, garlic, and collards
Warm season crops: tomatoes, pepper, eggplant, cucumber, melons, squash, okra, beans, zucchini, corn (takes up a lot of space),
Happy gardening in Hawaii. Gardens are where people grow.