What are some ways of saying "I don't think so"
Ex:
I don't think so
I think differently than you...
Another way of looking at it...
etc.

Question

Answer

我认为不是酱紫的……

Answer

a historical and rather brief version could be "非也" or "然也"
But if you want to be more casual,"I don't think so"equals "我倒不这样认为“，it will be quiet natural to present.

Answer

我不这么认为
我和你想的不同
用另一种方式想的话。。。

Hope they are helpful to u

Answer

I don't think so--我不這樣認為/我可不這麼認為。

Answer

1. 我认为不是这样子的。
 
2. 我和你的想法不一样。/ 我和你有不一样的想法。/ 我的看法和你不同。

3. 换一种方式（角度/ 眼光）看这个（问题/ 事情）。