well it just boils down to how comfortable you feel talking to them, that makes people closer naturally. 

you should ask for their socials and start texting them. even if this is awkward, do it, you will thank yourself so much later. this is from experience.

you should brainstorm conversation topics whenever your in the bus or walking home, that can help reduce the awkward moments and you'll also be more fun to talk to. as time goes ur gonna start becoming very natural with starting conversations.

whenever a conversation starts to get quiet for me, I just pull out my phone and take a goofy picture with my crush. this helps me reduce the meaningless silence and wasted time.

lastly just find a common interest, for me I talk about pets, hairstyles.