Below are some helpful links if you would like to get better with the basic of Riichi Mahjong.
Japanese Mahjong Strategy – puyo
Daina Chiba’s Riichi Mahjong guide on how to play better and efficiently (More than basic level, read this first)
Daina China’s Riichi Seminar 2017
Feng’s & Gabriel’s Intermediate Riichi Strategies Workshop in SMU Dec 2018
Riichi Mahjong Japanese terms