The number one criteria another person must fulfill before you decide to invest your time in them is a clear and consistent demonstration of their interest in you. And a clear demonstration of interest in you equals consistent effort. If someone keeps you wondering about their level of interest in you, their level of interest is probably not enough to deserve your time.
Your person will see your worth and value right away. They will be excited to get to know more about you and to spend time with you. And they won't just SAY these things - their actions will demonstrate these feelings. Here's the thing - if you don't yet see your worth and value, then you will feel attracted to and comfortable with people who don't treat you as someone worthwhile and of value. You will put up with inconsistent behavior, not being made a priority and will settle for crumbs when you deserve the whole damn cake. If you don't know that you deserve better, you'll never hold out for someone who treats you better. Unconscious attraction means that we are attracted to people who reinforce how we feel about ourselves. So if you aren't yet fully in love with you, you'll choose people who keep you guessing about how they feel about you as well.
What do you do if someone is not giving you consistent effort and attention? Communicate. Let them know that if they want to continue to see you that you need consistency and effort. And then watch what happens. If you scare them off, blow them a kiss goodbye and throw a damn party. Because anyone who can't give you consistent effort isn't meant to be in your life. If they tell you you're too demanding, let them know that they are allowed their perspective but that you will hold out for someone who doesn't see communicating needs as anything but healthy and adult behavior. People who scoff at or resist your boundaries are not people you want in your life. And telling someone what you need is a way to set boundaries. If someone says they understand and will do better, cool. But then watch their behavior. Words are cheap. If their behavior doesn't change, it's time to move on.
You are a damn gift to the world. If you don't know that yet, you have some work to do. Read some books. Find a therapist. Start talking to yourself like you talk to your friends. Expect consistency and effort. And if you're not getting that, move on. Every time you say "no" to the wrong person, you clear space for the right one to enter. If you allow people to be in your life that don't make you a priority, you'll get more of the same. And you deserve so much more than that.