If you are wanting to actually do your drawings by hand, the first thing I would do is invest in a graphics tablet, if you haven't already. It really makes all the difference when it comes to drawing things digitally. I personally use a Wacom Cintiq (mine's the 22HD model from a few years back), which I can recommend, but Wacom's products are defnitely more pricey. Huion seems to have a good selection of more reasonably priced tablets that I have heard a lot of really good things about, and that's probably where I would turn now if I had to replace mine. My partner uses a XP-Pen which also seems like an excellent product.
I personally steer away from Youtube as much as I can, I much prefer written tutorials over video one.
The Guild actually has a really good collection of Photoshop tutorials that I can personally recommend. I didn't know a thing about how to make maps or anything else with PS when I found this forum ten years ago, and it was the tutorials I found here that got me started. Here's a few town related ones I found in the PDF listings:
https://www.cartographersguild.com/s...ad.php?t=18390
https://www.cartographersguild.com/s...ead.php?t=1150
https://www.cartographersguild.com/s...ad.php?t=10421
https://www.cartographersguild.com/s...ead.php?t=4313
Some of them might be a bit older at this point, but defnitely still worth taking a look at. They can at least give you some ideas on how to approach things.
As for resources... Everyone is different when it comes to maps, but for me one of the most important tools in my trade are good textures. My own maps lean heavily into the antique parchment type of aesthetic, so for me my large collection of high definition paper and parchment textures are an absolute must. A lot of my best parchment textures come from this amazing collection by CoyoteMax, I've also made some myself, and the rest I've bought from Shutterstock. Textures.com also has a really good selection of seamless textures and patterns for things like rock, dirt, vegetation, tiles, water and the like for more realisctic, satellite style maps.