Obviously the more room you have for flowers and plants, the better your chances for attracting hummingbirds and birds to your garden. But just because you might only have a small yard doesn't mean you can't do anything. Here's a small brick planter we built in the easement between our sidewalk and the street. It's about 4' across (give or take). I've planted it with daylilies and annual plants (this year Salvia Lady in Red and Cleome - spider flower). These plants provide nectar for the hummingbirds, as well as spiders (did you know hummingbirds use spider webs to build their nests???) and insects (hummingbirds eat lots of insects!). Later in the summer and fall those plants that I don't deadhead will provide seeds for lots of other birds.
Last year the hummingbirds visited this area twice daily, like clockwork. Work with what you have!