The only 100% certain way to avoid pregnancy is to not have penis-in-vagina sex, or do any sexual stuff where sperm can get on a vulva or in a vagina (this is called abstinence).

But if you’re going to have vaginal sex, the best way to prevent pregnancy is to use a very effective birth control method (like the IUD or implant) plus a condom. The most effective methods for preventing pregnancy include long-acting reversible contraceptives (LARCs) like intrauterine devices (IUDs) and implants, as well as hormonal methods like birth control pills, patches, and injections. Barrier methods like condoms, when used consistently and correctly, can also be effective.

It's important to consult a healthcare professional to determine the best method for your individual needs and circumstances.