The most successful thing I've grown so far has been, hmmm, WEEDS!
This year, I was determined to put some color in our beds. Here are a few tips that I have used to decide what, where, how & when to plant.
1) Be realistic. How much time, effort and money do you really want to devote to this?
2) Plant according to conditions. My back yard gets the morning sun and my front yard gets the HOT, direct, afternoon sun.
3) Instead of planting in the ground, try planting in decorative pots. They take up more room and add a little umph. Also, if a plant or group of flowers doesn't do well in the pots, you can get rid of them and replace easily. You don't have to worry about bare spots in your bed.
4) Decide if you want to add color using plants, flowers, or a combination.
Here is a list of what I have growing (yes, they're still alive). I guarantee you that all of these plants require little effort and attention:
Begonias - Dark leaves/dark flowers for hot & sunny areas; light leaves/light flowers for less sunny & cooler areas.
Geraniums-My geraniums actually bloomed all year! They even bloomed during our brief (2 minute) snow storm! All I do is snap of the bloom all the way at the stem when it dies.
Caladiums-An easy maintenance, hearty plant that comes in a variety of shapes and colors.
Kalanchoe-My Mother-In-Law gave one of these plants for Mother's Day-and it's still alive! I only remember to water it about once a week.
Petunias-they only lasted through spring. I've never been successful keeping them through the summer. But, they are beautiful and slightly fragrant when their blooming.
For all of you black-thumbed gals, I hope this information helps. If I can keep these plants alive, anyone can!