I'm going to Seoul next month, any sisters recommend must-try beauty treatments?

Hi everyone! I'm Yun, and I'm finally heading to Seoul next month for a business trip and vacation. I'm really looking forward to taking this opportunity to experience the legendary Korean skincare management. I've heard that beauty clinics and dermatology offices in Seoul are incredibly professional, but there's so much information online that I'm a bit unsure where to start. Have any of you had skin treatments or beauty procedures done in Seoul? I'd love to hear your honest experiences!

My own skin is combination-oily, and it's been a bit dull lately. I'm particularly interested in trying the rumored skin boosters (water-light injections) and deep cleansing treatments, but honestly, I have no idea about the Korean procedures or post-treatment care. Can anyone share what the experience is generally like? For example, how far in advance do you need to book, and are the results really immediate? I also really want to buy some highly recommended masks and serums to bring back, but I'm not sure which products to trust.

Also, are there any specific areas in Seoul that are particularly recommended for beauty treatments? I've heard of a few commercial districts that specialize in this, but I'm not sure if it's true. In terms of budget, I'm comfortable with mid-range spending, but I definitely won't be splurging unnecessarily, haha. If any of you have been recently or go often, could you give me some tips? Like how to book, what identification to bring, what to be mindful of after the procedure... I feel like finding a reliable place is really important. Looking forward to everyone's suggestions!