First,you can make your lifelong friends at university(此句话太绝对,可以把can换成may或者其他委婉说法).You will meet all kinds of people during the four years,which is a good opportunity for you to make your(your可以省略) true friends.A real friend can let(make) you become a better person(这句也是太绝对,可以委婉说法.),not only in character but also the relationships(去掉S) with others.
注：虽然语法没有错误,但是太绝对的说法,会造成评委老师看着觉得你不成熟.
Second,you will become a mature person during the college(注意全文university和college统一,二者不是一个概念).I think that(it) is the most important benefit you can gain from the university,as a college student is high time to(主谓不搭配) learn to be an independent adult.Therefore,you should deal with your own affairs by yourself (以下部分不需要写until…,可以省略)until you can handle it completely.This can force you(缺to)grow up.
Third,university education is the foundation of your career.Network through various activities one participates in campus(本句不通.谓语是哪个?建议简化词汇,对把握不准用法的词汇,尽量避免).A good interpersonal network can help you to(常用help sb.do sth.或者with sth.) start your own career more easily than others after your graduation.
注：全文还算不错!继续努力!