The general standard in Tokyo is good enough that you don't have to worry too much about walking into a restaurant at random, but soba covers a range of experiences - from fast food stalls on station platforms where you can slurp down a filling bowl, standing at the counter, shoulder-to-shoulder with other travelers, to refined restaurants in historic buildings which sometimes display the soba mill in a window so that passers by will understand that the noodles are hand made on site from primary ingredients.

Since you want to learn about soba, I think you owe it to yourself to try a few points on the spectrum, from the austere (cold noodles on an upturned basket with a dipping sauce and a blob of wasabi) to the extravagant (e.g. with duck soup or tempura). You will find some variation in the coarseness, thickness, and the color of the noodles - This is related to the ingredients which can be 100% buckwheat flour or a mix of buckwheat and other flour (usually wheat, I think). And if you're very interested, you can also join a session where you will get the chance to make your own soba.

Tabelog is a good site to find places that are well regarded by locals. Here are the listings for Akasaka:
https://tabelog.com/soba/tokyo/A1308/A130801/rank/

JAL offers a pretty good introduction to the variations, with a couple of suggested restaurants.
https://www.jal.co.jp/br/en/guide-to...any%20toppings.

Soba classes:
https://airkitchen.me/list/tokyo/soba.php

Before you go to a fancy place, I would recommend that you get an idea of what the base-level standard is by trying a soba bento from a convenience store or a standing soba counter at a busy railway station. I expect you'll find it more palatable than the cheap stuff that you get from the Asian store back home.