First of all Stalk the person.
Wait..before you start to judge me .. I am telling this because with the social media of today we can know a person inside out through their social media handles.
Get to know about their likes and dislikes.
When in a common group of friends, discreetly introduce the topic of interest of the person you like. Like if someone likes the show FRIENDS …talk about your favorite character and ask ,” Who’s your favorite character character and why?”.
Get to know them little by little and make them feel comfortable in your presence.
THIS ONE WORKS WONDERS :
If you want someone to like you, you need to have their attention and if they don’t get the attention they crave for your attention more. So time and again back off a little. Its like when someone forbids you to have cake and even when you didn’t want the cake in the first place…now all you can think is ‘oh, i reason to eat it’.
That is, reverse psychology.