"I find learning English very hard, but I'm going to stick with it!"
"Stick to" usually means to join one thing to another using glue, or by some other method of actually joining two things together:
"You need to stick the stamp to the envelope before you post it."
"Rip up" : "I ripped the carpet up off the floor."
"Rip off": I ripped the wallpaper off the wall. "Off of" is a common error made by native English speakers too! But "of" is not required.