I plan to go from Mianyang to Dujiangyan and then to Qingcheng Mountain. Is there a better route? Especially about accommodation, riding and so on.

Mianyang Pingzheng Station has a through train to Dujiangyan. Then take bus no.7 (get off at the terminal) outside the passenger station to Dujiangyan scenic spot; If you stay, I recommend you to stay at Tianhe Shengshi Joy Hotel (not far from the scenic spot, but also cheaper and the environment is ok). To Qingcheng Mountain, go to the passenger center first, and then take the 11. (I don't know if there is a through train to Qingcheng Qianshan in Dujiangyan Scenic Area, so ask then)

If you only go to Qingcheng Mountain, 1. Pingzheng goes directly to Dujiangyan, and then turn 11. 2. Take the train to Chengdu North Railway Station, take the bullet train and get off at qingchengshan railway station directly.