On the beginning, the best information to your bowstring you can get by your trainer.
Kinryu bowstrings are somewhat more thick and suitable for beginners.
Hinokotsuro and Kaeru-tsuru are made of Kevlar and hemp.
Hibiki are Kevlar.
Hibiki red are for a draw weight from 10 to 18 kg.
Hibiki yellow are very thin bowstrings for more acceleration.