Answer:
What makes this a weak introduction is it doesn't introduce the purpose at the begining (which I am guessing is, "Cosmetic surgeries have various benefits but if they go wrong, the consequences can be devastating."(You need a hook)), it doesn't explain in detail about what the image of a person is, and you use a lot of 1st person words.
Step-by-step explanation:
Do not use "As" and "I can tell you that" in the first sentence. Simily say, "During puberty children experience many physical and psychological changes." For the second sentence you should say, "For example, our image of ourselves," then talk about what image is and explain it. Try to not use 1st person words too much like, I, we, us, and our.