Pretty much what Bobbias said. x.x I know how to get things set up, but I'm not really at a level of comfort where I can give solid advice or a decent walkthrough. Every time I've streamed I've just sort of flown by the seat of my pants. ¯\_(ツ)_/¯
As someone who's done a bit of radio, did some recording one time for a YouTube thingie, participated in someone else's streaming event, and is an avid content consumer, I can give a little bit of general advice:
First (and most importantly), get a decent mic if you plan to talk and learn how to properly use it. The "using it" part seems obvious, but a surprising number of YouTubers and streamers don't practice decent technique and don't have good configuration. Get used to keeping your distance and inflection fairly even, if you can't use a pop filter (or are using a headset with limited capacity for one), make sure that you have your mic positioned in such a way that it isn't affected by plosives (loud bursts of noise caused by sounds like hard p's) and can't pick up your breathing. Running it through a compressor will help to even out the levels as well.
While this isn't essential, considering investing in a setup that will allow you to do live monitoring. If you use the right kind of headphones, it'll prevent game audio from feeding into the mic, will give you a solid idea of your audio mix in real-time, and will make it easier to keep your voice level consistent (if your voice starts to get lost in the mix you'll hear it instantly). I'm a fan of having an analog mixer taking care of the mix, since modifying mix settings can be done with a few slider/knob tweaks.
This should be doable on Windows, but when I was doing recording on my iMac I had a couple of USB interfaces (one for game/system audio and another for VoIP) going into a Behringer mixer, which then fed into the iMac. I'd set Discord or whatever to output through the VoIP interface and everything else to output through the general interface, and the computer's input would be the mixer's output. In total, the mixer had my mic and the two interfaces plugged into it, with a pair of headphones plugged directly into the mixer. I had full control with that setup. I could choose which channels went to both the master output and my headphones and which ones only went to my headphones. This would allow me to freely include VoIP audio in the mix if I wanted without having to dick around with OBS.
As far as the actual gameplay stuff is concerned, do a bunch of private recordings first and practice your commentary. This kind of serves a dual purpose, as it can get you familiar with OBS's interface as well as let you practice talking to yourself. It's one thing to talk to someone but it's another thing entirely to roll solo and just shoot the shit into a faceless microphone. If you're just starting out you're not going to have a big chatroom to interact with, so you're going to have to be comfortable with doing a lot of talking if you want to take that sort of approach. Playing back your own recordings will also help you identify any tics or behaviors that you might want to work on before going live (um's, ah's, excessive salt, etc) and give you a good idea of how you're going to sound to your listeners.
I know that wasn't exactly what you were looking for, but I hope it helps!