Chengdu to Jiuzhaigou and Huanglong

Thanks in advance for the advice..we are planning to visit the subject locations from mid October on.
Could you Folks help to give us your expertise advice...as follows:-
(1) From Chengdu..what will be the best mean of transportation to JZG and Huanglong?
(2) Are there any local tour that we could join from Chengdu to these locations, or we could join a local tour over at JZG and Huanglong?
thanks again for my ignorance for the subject matter..
thanks again
terry