We can study Yan Zhenqing's "Sacrificing a Nephew" or "Contending for a Seat", both of which are famous calligraphy posts of Yan style, especially "Sacrificing a Nephew", which is known as the second calligraphy in the world.
If you don't like Yan Ti's running script, you'd better start with the Preface of Wang Xizhi collected by Huairen, and you can choose Wen Ya's Zhao Mengfu running script or Mi Fei running script with more personality.