These are not very safe – they rely on you knowing when a woman is fertile, and not having sex or using a condom 100% correctly during that time. The woman has to be prepared to monitor when she is fertile, by maintaining a calendar, or watching her discharge (stuff that comes out of the vagina) very carefully – every month.
You and your partner need to be very committed to stick to these methods, and prepared to deal with the woman becoming pregnant if it fails. And these methods don’t protect against STIs and HIV at all!
If you want to use natural family planning, please go and get training from a doctor or nurse.