Opportunities to attract hummingbirds across the continent can vary greatly, dependent on your location. Some people don't need to do a whole lot to attract hummingbirds due to the high population in certain regions, and some people have to go to extraordinary measures just to attract one because of low populations in others.
Hummingbirds are not complicated creatures to understand, but they are extremely complex in their abilities. The very first thing we need to know to attract hummingbirds is that they are opportunistic. Food motivates them. The more food you have available, the greater chance you have to not only attract them, but to attract many, and keep them returning. Color represents food, and the more options you have, the more secure they feel in their survival. If you provide one food source, their survival is dependent on that one food source not running dry. Most plants have a season that they produce nectar, and that season is oftentimes very short, especially with perennials. When that perennial runs dry, the hummingbird then requires a different source, so the more sources you provide, the much greater likelihood of the hummingbird or birds sticking around.
One feeder can attract them, but half a dozen feeders prove to them it's a worthy location. A few flowers can get their attention, but they know they're insufficient for survival, so plant many. Just like your eyes light up when you arrive at a food court with several delicious options where the smell permeates everywhere, a garden filled with flowers and feeders covering the territory is certain to get their attention. Eventually, when a mother hummingbird leaves the nest with her young, she'll head to a land of promise, were food options are abundant and never run dry. Truthfully, you could never plant too many good choices for hummingbirds. Don't limit yourself, but use the space you have to let them know it's a serious contender for their attention.