Advice first time visiting Thailand :)

Hi! Me and a friend (we are both F24) are visiting Thailand for the first time in March. We are in the process of nailing down our itinerary and booking hotels.

Lately we've seen a lot of mixed feelings and opinions about being a tourist in Thailand. Things regarding bad air quality, overcrowded places, unclean beaches, etc.etc. So we are trying not to let it get to us, as we both feel like we've read mixed reviews about prior destinations we have visited as well, but they've all turned out fine, but we're still getting a bit nervous.

We're looking at visiting Bangkok, taking a few day trips from there, then flying south to explore the Phuket and Krabi area. Regarding accommodation in Phuket/South, is it best to just stay in the same hotel in for example Phuket and explore both Krabi and Phuket area from there, or is it too difficult to get around making it easier to relocate to Krabi when we want to explore that area?

We are going just to explore the different places we visit, sightseeing, beach vibes, and some party vibes but nothing crazy. Any tips for places to visit, places to avoid, things to calm our nerves, and tips for traveling in Thailand in general are very welcome!