Consider What You Can Grow
The fact of the matter is that certain fruits, vegetables and plants will always grow better and be healthier in certain parts of the world at certain times of the year. Tomatoes, for example, grow best during the summer while carrots and pumpkins often flourish during the winter. For best results, always know the zone you live in and what will grow best for you at different times of the year. You may be able to force tomatoes to grow in the Winter, but they are rarely as good as they are in the summer.
Choosing good soil and good fertilizer is an important step towards growing healthy plants. If you are unsure about the quality of your soil, you can have it tested by a lab, test it yourself or you could simply conduct an experiment of your own. Plant identical seeds, give them identical care and the same fertilizer but plant one branch in your existing soil and another in an area with healthy soil you have gotten elsewhere. If one batch grows much better than the other, you know whether soil is adequate for planting.
For an area that is very wet or that expects to have a lot of rainfall, a raised bed is a good choice. A raised bed can be made out of wood, concrete blocks or even old tile and hardwood flooring. You will need to verify how tall your bed should be and to make sure that you have enough product to fully enclose the garden. It is also interesting to note that you can have more than one raised bed, sectioned out at various intervals throughout your yard or you could simply have one that holds particularly fragile or important growths.