The 39-year-old supermodel admitted that she had to establish herself as confident and smart in her career straight from the outset.
She told Ocean Drive magazine: "When you have a good body, photographers will often be like, 'Yeah let's take this off, and why don't we lose this too?'
"You can quickly end up not wearing much clothing. You have to be careful and strong at saying no, especially when you're younger and on your own. Not everyone is cool and has your best interest [at heart]."
The mother-of-four also explained that you have to be careful of others without treading on their toes on the way to the top.
She continued: "I've learned to not be scared. When you're young and pretty, you can't be vulnerable.
"Not that I'd hurt anyone to get to the top, but you have to bring your hustle and watch your back."
Klum also revealed that when signing up for a Braun razors deal she found out one of her limbs is worth more than the other.
She confessed: "In London, I had to go to an insurance firm and this person just checked out my legs.
"On one knee, I have a scar from when I fell and had to get stitches, so they made that leg less expensive than the other. But I went with it. And obviously, it's all very flattering."