1. The real trick to managing your money is not what you do — it’s how you do it. 

2. The main trick to use in any of these circumstances is the right set of keywords. 

第一句有误。to managing 应改为不定式： to manage。这里，trick 指“技巧；诀窍；窍门”，跟 way （方法）的用法相同，用不定式作定语。

第二句正确。网友应注意不同的句子结构。第二句的这个不定式跟上句的不定式不是一回事。虽然 to use 也是作定语修饰trick，但 use 是及物动词，不能没有宾语，其实它的逻辑宾语就是trick。意思是“去采用的诀窍”，我们可以在 to use 前加一个逻辑主语：The main trick for you to use。

关于 trick 之后接不定式作定语，有词典例句为证：

1. They had to think of a trick to get past the guards.  

他们只好想出个计谋骗过岗哨。

来自《权威词典》

2. That was a contemptible trick to play on a friend.  

那是对朋友玩弄的一出可鄙的把戏。

来自《现代英汉综合大词典》

3. So this had been a trick to lure the tiger from the mountain! Zhu Laogong's lungs nearly burst with rage.  

朱老巩明白过来,是调虎离山计, 一时气炸了肺。

来自《现代汉英综合大词典》

4. That was an unfair trick to play on her.  

跟她开那样的玩笑太不好了。

来自辞典例句

5. I can't open the box —— is there a trick to open it?  

这箱子我打不开——有什么好办法吗 ?

来自辞典例句