This popped up in my YouTube feed earlier today and I found it quite useful. I'd add one tip of my own: gloves.
Whether it's descending on a hot day where your palms are already sweaty and you're sliding around on your drop bars or a hard ascent in the rain, having good and tight-fitting cycling gloves that wick away moisture and help you grip your bars confidently, is going to be useful.
I slipped off the drops and the hoods of my gravel bike more than once on a fast and tricky descent and it's luck that I didn't crash hard at times. Gloves made all the difference for me.
One important thing to look out for when buying gloves is that they don't have seams in places that will cause pressure spots or chafing when using drop bars. Many gloves are made with mountain biking and flat bars in mind. Try them on, hop on a drop bar bike, and get into the various positions you're riding in most frequently.