Sure! I don't know how useful this is, but it's some stuff I do when I'm doing art assets and thing.
You might know already that MV's default tile size is 48 x 48 pixels per tile. For polar seven, I designed the sprites and tiles around a 16 x 16 tile size and then upscaled them by 3. I find working in that smaller resolution less intensive than trying to draw everything at 48 x 48 and I'm used to making sprites at that size from previous RPG makers, so that's what I generally do. If you try this out, all you have to do is make sure you're upscaling and downscaling with Nearest Neighbor as the setting in whatever art program you use, to avoid anti aliasing. You can also design things at 24 x 24 and then double them.
That's how I do things with pixel art, anyway. Things would be a little different if I was like drawing assets, which some people do and I haven't done in a long time. smaller canvas sizes would probably be uncomfortable for that style.
MV's documentation has the different asset sizes and stuff near the tail end of it, but I usually have these templates on hand for laying out tiles for the different tileset types:
https://invenblocker.tumblr.com/post/161891747018/templates-for-rpg-maker-mv-til...
The autotiles can be kind of difficult to make though, I don't do a lot of them because they are hard to visualize. If you feel unconfident with them (I usually do) you can get a lot out of just using A4 (walls) and A5 tiles with B-D, for the most part. To visualize how those work I use this graphic:
https://www.reddit.com/r/RPGMaker/comments/mil04n/autotile_template_for_mv_made_...
At the tail end of that reddit, someone has an Aseprite file that I have yet to try, but allegedly automatically displays how the autotile would look in full as you draw it, which seems very handy. I'm fixing to try that out next time I get the chance. There are also a good number of youtube videos explaining how autotiles work. They're trickier to design than the other tiles, is all.
Making pixel art is kind of a whole thing, there's a lot of tutorials on https://lospec.com/. I also use them to sources palettes on occasion, since palette design is a skill unto itself.
There's also a lot of plugins out there for tweaking aesthetic things, Like I usually disable the cursor blinking and have fully opaque windows since I find the transparent ones kind of distracting (and inauthentic if you're making deliberate homages to like NES/SNES games). I typically have Aries's free customizations plugin from here handling the cursor (https://ariesofsheratan.itch.io/aries002-systemcustomiser) and have Yanfly's suite of plugins slotted in and their core plugin handles the window opacity. They have a free essential bundle that I believe includes the core plugin (https://yanflyengineplugins.itch.io/). Galv (who has an external site) also makes a lot of free MV plugins that I see cited pretty often, though sometimes there is compatibility issues. Himeworks and SumRndmDde (SRD) also make a lot of plugins and I see their names come up in credits frequently. Many of these include aesthetic tweaks you might be interested in at some point, so just including them for future reference. For example, I use SRD's plugin that makes the sides of the window border tile instead of stretch all the time when I'm using pixel art.
I won't prattle on, but hopefully some of that is helpful? That's like my general environment for sitting down and making assets for MV. I'm not sure how useful any of it will be for just starting out. I use Aseprite for a lot of the work since it can do tiled canvases, which helps a lot when trying to visualize how tiles will look laid out next to each other so you can get rid of the visible like, seams. I can try to field specific questions, but that's sort of the off the top of my head stuff!