How do I say "convince (someone) that (something)"?
To convince:



to make (someone) believe = "使.....相信"



Example: 使她相信 (make her believe) 這不是她的錯 (that it is not her fault)



to make (someone) +(verb) = "說服" +(verb)



Example:  說服( convince)她相信 (her to believe) 這不是她的錯 (that it is not her fault)

*相信 in this sentence is a verb that can be replaced with other verb, for example: "deny"


  I should convince her that it is not her fault.


base on the context of in this sentence, you are not convincing her to act, but convincing her to believe, so "使她相信這不是她的錯" is the  appropriate phrasing.