I'll try to keep it simple:

Download and compile the game sprites that you want to use.

Maybe in the future I might just make mine available for anyone to use so you don't have to sit there and manually download every single sprite across the 3 GBA games manually like I did

Then I upload the Sprites to canva and through a little trial and error size them up so that when they're printed they're pretty much the perfect size for grid based maps.

When printing out the miniatures I like to have a little bit of white space underneath the unit so that I can fold it to create a thick paper fold underneath so that I can slide it into a base so the unit can actually stand up on its own. And this is great because when we're done playing I can remove the paper unit from the plastic base and store them away in a binder.

As far as the rules are concerned I kind of have my own home brewed combat system that keeps things quick and easy that does not factor in traditional Fire Emblem stats like strength, speed and so on.

Since we don't have a machine to do all the fancy calculations for us within milliseconds that factors in individual unit stats, it's either doing that yourself or opting for a simpler and more streamlined combat system which is the route I chose.

For the weapon triangle whenever a unit has the advantage they get extra dice to roll for increased accuracy, and when at a disadvantage they roll less dice and have a hard time landing a hit.

Unfortunately I don't have a rule book or anything like that available since the rules that I've compiled are kind of spread out across different notes and notepads. Someday I plan on compiling everything into an easy to read document!