At this point I don't care what you decide to do.

到这个时候，我不在乎你决定要怎么做了。

You first have to decide to do it.

首先你必须下定决心去做。

We decide to do it on your suggestion.

我们决定照你的建议做。

What'd you decide to do about the movie?

你决定那部电影该怎么办了吗？

We decide to do so.

我们决定这样办。