Crushes are a part of growing up. Everyone experiences them at some point or another in their lives. For everyone, it's different. It's all normal, but sometimes it can be stressful as well.
It's possible that you might have a crush on someone if you feel nervous around them. You might want to try to impress them either consciously or subconsciously. Another common symptom is that you want to be with them a lot and feel jealous if they spend time with other people of the opposite gender.
There are both good and bad sides to having a crush. Some good signs are that you feel happy and excited when with them and that you enjoy being with him or her. However, the bad signs are that you could neglect other things in your life (friends, family etc.), get possessive of the person or experience rejection. It's important to look at the good and bad sides of it.
To get to know your crush a little more, spend more time with them. You can call for them if they live in your estate or sit next to them if they're in your class at school. Try to connect with them. Before you can start going out, you need to be friends.
When you become closer, you can suggest going somewhere together. However, choose the location carefully. It needs to be somewhere that you can agree on. Going to the cinema on a first date is not the best idea, unless you go somewhere else afterwards, because you can go home and realise that you barely spoke to each other at all. If you both like music, you could go to a CD shop, or if you both like fast food, you could go to MacDonald's. After a few dates, you can ask for their phone number (if you don't already have it). This will provide an easy form of communication for both of you.
It's important to subtly let her/him know that you're interested, but at the same time, take it slow. If you rush things, you might find out that they don't like you in the same way, which can cause tension. Remember, even if things don't work out, you still want them as a friend.