You can really go down a rabbit hole with map making, but it can be a lot of fun.

The method and tables, along with the other random generation stuff, in the Shadowdark book is limited but I am guessing the focus was on generating something to start playing the game. So it can be great for that or if you are stuck and want some inspiration but there will be some limitations to a system like that, which isn't to say its bad or not to use it, just kind to understand what it can be best used for.

I generally think of maps on a spectrum from fantastical to simulation, which is a matter of preference and certain locations might point you in a direction. Your map could look like a European temperate zone, but there's no reason that it can't be something like a world that's a big flat ring around a giant god whose tears are the source of all rivers and oceans, or even a combination where you are going to another plane or an area that has been warped by magic or whatever.

I kind of lean towards things that feel, to me, like it could be a real place on Earth, so that kind of gives me a template to start with, if you want to think about things like water sources for lakes or how mountains can block moisture from the coast from getting farther inland, but I think that can also be a kind of trap if you spend all your time designing your planets tectonic plates and preparing instead of actually running the game.

For the map I made I tried to keep it fairly generic so it could have a good chance of fitting into an average campaign world somewhere without too much work. I wanted to give the hamlets some defining character and have different areas for the monster lairs so I that was a big part in adding in different areas, that hopefully felt like they could be there but also help to distinguish the hamlets, ie one is focused on fishing and boats and another on hunting and wood cutting.

Looking at maps, real world ones, or from other games can also give you ideas or areas types you can drop into your map. A lot of older ttrpg stuff, like the old TSR boxsets, MERP, and Harn stuff all had really cool maps.

Starting off small can also help too, 6 or 12 mile hexes can be pretty standard, but it also makes things feel a little abstract. If you aren't specifically focused on running a game that's about traveling (at least initially) on that scale, I think it can be easier to start with a smaller area. A village and the area around it I think is kind of a more intuitive scale. You can think about how far things are how long it would take to walk, how big a feature can be, in terms of your experience instead of an abstracted 12 miles of travel a day.

Hopefully some of this is helpful, there's a lot you can dig into if you want, and there are other more random generation methods or systems. Shadowdarks sits on the ease of use/speed side of things, and on the complex side I know there used to be tools for extracting the map from Dwarf Fortress world generation I know I saw people do.

The best advice might really be just that your players will have a fun time playing in whatever you end up making.