What ampoule is good for sensitive skin?

I was born in 2014 and have dehydrated oily skin. My skin is sensitive, so if I use the wrong product, my skin breaks out completely.

Also, since I get really tanned in the summer, whitening cosmetics are good too!

Since I'm a student and don't get much allowance each month, I try to find the most cost-effective items possible!

Please recommend some basic skincare products (ampoules, toners, pads, serums, essences, etc.) that are gentle, brightening, and cost-effective.

It's even better if you find it at Olive Young😍