をとるために

in order to take/get …

→ を
phrase Rare #39,384
in order to take/get … Follows the object being taken or obtained; とる can mean “take,” “get,” or “obtain,” depending on context.
JA: 写真をとるために、カメラを持ってきました。
EN: I brought a camera to take pictures.

よい席をとるためになすべきすべては早く出かけることだ。

All you need to do to get a good seat is leave early.