Tips For New Gardeners
Plants die, so get over it. The most important thing that gardeners should realize, is that every living thing has a prescribed life span. Sometimes plants die for no earthly reason whatsoever even though you've done everything "right," Don't obsess over it! Dig it up and plant another.
ALWAYS plant the right plant in the right place, or another way of putting it, suit the plant to the site. Don't try to plant a Hosta in a prairie garden, it ain't gonna work. Conversely, don't plant something that likes it hot and dry in a moist, shady spot.
ALWAYS keep in mind the mature size of a plant/tree/shrub. The biggest mistake that people make is initially planting things too closely, not realizing how large something will grow. Then 3 years down the road they're complaining how their perennial bed is crowded and overgrown. A rule of thumb is to plant something the distance of 1/2 its size, i.e., if a plant grows 2' wide, plant it 1' from its neighbor.
Start small. Build one 4' X 8' bed or till one 25' X 25' patch. A new gardener has to build their skill and make time for gardening into their lives. Take more time thinking, than ordering from catalogs. The more time you spend in your garden planning, the greater the odds are you will take the time to find out where you really want things placed. Moving an improperly sited apple tree gets a lot less fun 4, 5, or 10 years after the fact. Moving them to a new site is often a bigger job than just digging a new hole a bit bigger than the root ball.
Feed your soil, not the plant. The secret to a great garden is great soil. Try to add large amounts of organic materials like crushed leaves, grass clippings, and homemade compost. Your plants will never be happier.
There's nothing special about seeing dirt in between your plants. Mass your plants. Massing doesn't mean overcrowding. Plants that touch and overlap slightly create their own microclimates, thereby keeping out weeds.
A garden based on flower color alone is boring! Plant your garden keeping in mind foliage color, texture, and winter interest. As garden writer Ann Lovejoy say's if you can look at your garden in winter and like what you see, you've got good design.
Again, don't obsess over something that doesn't turn out right! Gardening is supposed to be fun!