Sure-fire
Part of speech: adjective
Definition: certain to work
Successful
Part of speech: adjective
Definition: Resulting in success; assuring, or promotive of, success; accomplishing what was proposed; having the desired effect; prosperous; fortunate; happy
Example sentence: Always believe in yourself and keep going. You don't have to have the most talent in the world. You don't have to be the smartest person in the world. If you persist and you persist and you persist, you will be successful.