"提高自身颜值" 的英文表达是 "improve one's appearance" 或者 "enhance one's appearance"。这两个表达都表示在外观上做出改善。

"Improve" 是一个动词，意思是使变得更好，更优秀。"Enhance" 也是一个动词，意思是使变得更好，更美好。

下面是一些英文例句和中文翻译：

"I want to improve my appearance by getting a haircut and buying some new clothes." (我想通过理发和买新衣服来提高我的颜值。)

"She uses makeup to enhance her natural beauty." (她使用化妆品来提升自然美。)

"He decided to start exercising and eating healthier to improve his appearance." (他决定开始锻炼和更健康地饮食来提高自己的颜值。)