I'm thinking of taking an advanced engineering course with him.
think of sb./sth. as意为“认为某人/某物是”。如：
People now think of the car as being essential. 人们现在把汽车看成是必不可少的。
think better of意为“改变主意”。如：
She wanted to say something, but then thought better of it. 她想说些什么，后来又觉得还是不说为好。
think highly of sb. 意为“看重某人”。如：
The management thought highly of him. 管理层很看重他。