Most things in life require a lot of planning, and making a beautiful planter is no different. The first step to making a planter is choosing a location. Sunlight is a very important factor to making a planter that will thrive. Weather it will be on a covered porch or out in full sunlight will determine what type pot you need and what plants you can use.
Next, you want to choose the right pot for you. There are literally hundreds if not thousands of different styles of pots to choose from. Pots can be big, small, tall, short, long, round, square, and they come in many different colors. The size, shape, and color of your pot will determine what size plants you can use and how they can be arranged in the pot.
Now for the fun part: Choosing plants. First and foremost, always try to plant in odd numbers for a more full and balanced look. Next, just remember these three words and choosing plants becomes very simple. "Thrillers, Spillers, and Fillers." A Thriller is generally a tall, skinny plant that will be the centerpiece of your pot. It can be a perennial shrub or tree such as a Boxwood or a Dwarf Alberta Spruce. Or it could be a tall annual plant such as Coleus. Spillers are trailing plants the will cascade over the edge of your pot. There are many unique options for spillers. You can use herbs such a Thyme or Oregano. Perennial plants such as Purple Heart or Ice Plant are great choices as well. There many great annual Spillers too, such as Sweet Potato Vine or trailing Petunias and trailing Pansies. Creeping Jenny is a very popular option due to its bright green color is vigorous growth habit. Last, but not least are Fillers. Fillers are used, of course, to fill in the spaces after you've chosen your Thriller and Spillers. Fillers should be shorter than your Thriller, but Taller and less wide than the Spillers. Some great choices for Fillers are Pansies, Petunias, Impatiens, Aster, Begonias and many many more. Don't forget to keep the color of your pot in mind and find plants that contrast well with it, and always read the tags of plants you buy to learn spacing, sunlight, and water needs.
When it's all said and done there is no "wrong way" to make a planter. After all, it's a work of art and art has so many different forms and interpretations. There's nothing wrong with an abstract planter. It's more important to just have fun and make it your own rather than follow a formula.