Unfortunately don`t have much expirience in those chiptune and 8-bit genres. Made couple demos for interest, and that`s all. And not in the proper DAW =)

Start out by doing covers - just remake NES songs you like as closely as you can.  Not only is it a good way to learn how to actually use Famistudio, but you'll pick up on different ways to use the different channels.  One example - I never would have thought to use a triangle wave as part of a drum without hearing it first.  Note that Famistudio also comes with a ton of sample files that are actual NES music pieces that you can take apart, mess with, and learn from.

For channels, the usual setup is for the main melody to be on Pulse 1.  Use  Pulse 2 for harmony with Pulse 1.  Each pulse channel duty cycle has its own characteristics that you'll get used to the more you experiment.  The Triangle wave channel is usually your base and the Noise channel is the drums (Note: the Duty Cycle also affects the sound of the Noise channel so play around with it!.)  DPCM is most often used for drums as well.  You'll want to watch the tutorials on those - they're a game changer!  Once you know the basic rules of each channel, you can start messing with them and using them for other things, such as Triangle for melody and a Pulse for the bass!

Speaking of tutorials, the Famistudio tutorials are also extremely detailed and worth a watch.  I watched them after I made my first soundtrack and still learned a ton.  Things can actually get quite complicated when it comes to creating instruments - I'm still learning that part myself.

If you want to change your songs tempo (BPM,) click the gear icon next to the song's title on the song list in the upper right.  Click the BPM dropdown and select a new BPM.  If the BPM has a star (*) next to it, it is an "Ideal Tempo," which means the notes will be perfectly divided and nothing will get messed up. (It took me forever to figure out how to change tempo in this thing lol)

If your melody sounds too grating or "tinny," try decreasing the volume on the channel.  You can do that by clicking the VERY small arrow next to the magnet icon right below your channel list.  This brings up your channel effects.  Click the "Volume" button.  Then, to the right, click in the timeline where you want to change the volume.  Drag it up or down to where you want it.  This has solved the problem 9/10 times for me, unless there is just something fundamentally wrong with the piece.  There are other effects you can put in as well.

That's about all the good tips I can think of off the top of my head.  If there's anything I did in my soundtrack that you'd like described in detail, feel free to reach out to me on Discord!  (Discord name: "ayback")

Yeah working with chiptune stuff is annoying at least to me.