How to properly set up ACL policies on amazon S3?

Question

Amazon Web Services

I can not understand. There are so many complicated settings out there. I can't even use a generator.
I need a very simple solution.
Now I upload backups there once a day, via cron and aws s3. And the bucket is there now - public. How to properly restrict access? That is, I should always have access through the console / site, from anywhere.
And my cron and aws s3 on my site, too. But for them, I think, more limited access. Or by ip, or by a set of operations. In general - I'm confused. The main thing is to let strangers on my view my bucket.