It took me about two months to first get a lucid dream. Since then, I get lucid dreams whenever I want using DILD (where I realize that I'm dreaming). In real life, I'm a pretty observant person, so it's easy for me to realize that I'm dreaming.
Focus on the details of the dream, and try to find something that doesn't make sense. In a school or work dream that is repetitive, I would go to the bathroom and look at myself in the mirror. Your reflection would be very distorted & you'll realize that you're dreaming.
Another reality check would be to try to walk through walls in real life (you can't), and in dreams try to walk through them & you'll see that you'll be able to.
Having a dream journal helps to make dreams more vivid (helps with hazy dreams) and also to remember dreams, so that you'll start to see that your dreams have the same patterns.