The best advice to give a beginning gardener is to do whatever the successful neighboring gardeners are doing, when they do it. They have learned from years of experience how to be successful in local soils and climatic conditions.
Make friends with a neighborhood gardener whose success is indicated by lush garden growth. Also join a local Gardening Club or Internet Forum where you can get answers to most of your questions. We invite you to post questions Here.
Determine what gardening "Zone belt" your garden is in. Maps are marked roughly West to East according to annual climactic conditions such as temperature, rainfall, sunshine, and soil structure.
Different Zones are best at growing different plants and trees. Cabbages grow well in the Northern Zones, while Pecans do better in more Southern Zones. Seed packets may specify a range of Zones. Seed catalogs often display the Zone maps, and indicate which seeds do best in which Zones.
Some Plant Varieties have been created that do well outside their normal Zones. But the best results will often come from native varieties. So check with your friendly neighbor about which varieties do best in your locality.
You may have tasted a certain fruit or vegetable that made a lasting impression. That same variety planted in other soils and climates may be much less impressive. So don't be disappointed with your initial attempts at a certain variety. There may be other varieties that will prove much more acceptable in your particular garden.
You may want to have your soil tested for acidity, which is called its ph factor. Some plants love acid, others prefer alkaline conditions. You can change specific planting areas to accommodate the plants in that area. Lime and acidifiers will change the ph. Be careful to group plants with similar ph requirements.
There is also the subject of fertilization. Some plants are "Heavy feeders" that require lots of nourishment. Others require very little. Many gardeners swear by Organic methods, others are content with chemical substitutes. You may be duly impressed if you try to grow worms in a bag of chemical Fertilizer.
Be aware that there are gardeners who Mulch their plants so heavily that weeds are unable to grow, and the worms that digest the mulch from underneath provide an added nutrient bonus. The Mulch also retains moisture by excluding the drying sunshine which allows for less frequent watering.
Potatoes planted in Mulch can be harvested without digging them in or digging them out, which prevents harvesting damage. Mulch also keeps the soil cooler, which some plants enjoy, but others do not. So study and become experienced and become expert.
You can change some elements of your garden by adding soil amendments such as sand or sawdust. You can also build hills or raised beds to provide better drainage for plants that don't like wet roots. But be aware that these beds may need more frequent watering than a level garden. AND . . . remember to Rotate your crops.
Don't plant water-loving plants unless you plan to install sprinklers or irrigators, or stand there with hose in hand. And don't plant Cacti in Wetlands. Go with the flow;
"When in Rome, do as the romans do" is good gardening advice.
You may have to buy Bananas from your local Grocer.
But your local Grocer may come to you for his Carrots.