Disclaimer: These are based on personal experiences.
Though these things vary person to person still it may work in your case.
Try to be polite not only with you crush, but also with people around you. If someone likes you that will be only because of you nature.
2. Be A good listener :
Than being a speaker, be a good listener. Listen to them. Don't just keep speaking. People will feel good when someone listens to the things going on in their life.
3. BE HONEST :
Be honest and sometimes tricky too..! Don't fake things to impress them. Later that will be your weakness. They ll expect the same act from you every time, you have to do drama the whole life.
4. DONT BE FAKE :
Be real with your life, honest with your words and loyal to them. Just show who you are. Your character, your skills, your dreams everything.
5. START SHARING :
Start to share everything happening in your life. Your day to day routine. So that you can make them feel that they're your priority. Make them feel important. Share all your likes and dislikes so that it would be easy for them to understand you.
6. EFFORTS :
Don't stop making efforts. If you suddenly stop making efforts after few days they can think that you were around them just to make benefits.
7. PERSONAL SPACE:
Give them their personal space. Don't let them feel that you're over-possessive person. No one likes to be in a suffocated relationship. Every time asking many unnecessary questions.
8. SPEND TIME TOGETHER:
Than to start a relationship in chat. Better hang out with them. So that you can know more about their insecurities and their taste of choice. It would be easy to vibe with them.
Try all these tricks and let me know if they're working for you...