Bieber, 19, has come under fire recently for his allegedly bratty behavior towards fans, photographers and neighbors.
Asked what advice he would give Bieber, Garrett, now 51, told Fox411: "Do not believe your own publicity. Sussing out who your real friends are is full-time work. Every scum bag, every drug dealer, every chicken hawk wants a piece of you. ...
"When you've got that sort of power at that young age, and everything at your doorstep, you put out that bad boy image," Garrett added. "At that age, testosterone, hormones, all of the money, you see what else you can get away with. He's also doing a lot of charity work."
Garrett's film credits include "Bob & Carol & Ted & Alice," "Walking Tall," "Sgt. Pepper's Lonely Hearts Club Band," "The Outsiders" and "Thunder Alley." His career was sidelined, however, by numerous arrests and years of battling addictions to drugs and alcohol.
Garrett's website said he will be featured on Tantric's next album, "37 Channels," which is due out Sept. 17. He recorded guest vocals on the track, "My Turn."
"It's an absolute honor to have such a iconic artist such as Leif Garrett on my record. I know that his voice is cooler now than ever in my opinion. Not much more to say. I'm just honored to have him on it. Rad as [expletive,]" the band's front man Hugo Ferreira is quoted as saying on Garrett's website.