Gardening takes a little work and a little patience. But it doesn't take an expert. I recently happened upon a blog in which the author, a well-schooled horticulturist, worried that some horticultural, landscaping and garden-design experts might be taking a lot of the fun out of gardening.* I've seen many gardeners become down in the dumps when they follow all the "instructions" but don't get the results they expected. As a gardener, I have failed at things that are supposed to be foolproof and succeeded at the supposedly impossible. For me, the surprises keep it all interesting.
My gardening approach at our home of 14 years has involved continuously amending with compost the sorry soil we inherited. Out of personal preference, I don't use chemical fertilizer. I rarely even use commercial organic fertilizer. I've often ignored what I've read about fertilizing, mostly without consequence. Dahlias, for example, are invariably described as being heavy feeders. Yet I've never put an ounce of fertilizer on mine and they bloom and re-bloom profusely every year. As for my garden's design, I do it mostly on the fly. In spring, I inevitably play a game of musical chairs with my plants, giving little sway to warnings that certain plants don't like to be moved. If a plant is too much of a diva, then I guess we're just not going to get along.
I'm not suggesting you should buy a plant, especially an expensive one, and ignore its fundamental needs. You can learn a lot from experts and their experiences and from the thousands of years that plants have shown people how they prefer to live. But gardening is an intensely personal experience, and doing your own thing can produce unique rewards. If you've killed a plant, even though every gardener you know says it's bulletproof, keep your chin up. There are plenty of other wonderful plants that will appreciate you for who you are.