To be safe you should go up a ladder one rung at a time.

为安全起, 登梯子时你应该一一爬。

I’ve put new locks on all the doors, and just for good measure, I’ve put locks on all the downstairs windows too.

我已经在所有门安了新锁，为更安全起，楼下所有的窗子也加了锁。