I did complete the game once on lower difficulty, so I want to share some thoughts and hints:
My preferable playstyle is just give everyone the harder hitting short range weapon and human-wave everything. So, It is obviously not the best, but rather best-enough point of view.
So, my very personal hint: you may pre-stun your troops by various ways, so they drop before they die.
Gal to Peasant ratio?
If you have patience and discipline you can go 100% Peasants. Just explore the game, find all the options it gives, try all the damage types, etc. It is probably the most strategically and economically comfortable way, cause peasants are cheap and low upkeep and are capable to do anything sooner or later. Yet, I personally did 100% Gals because melee everything-throw bombs are fun. And there is no shame in being poor.
Best early pistol/SMG/Rifle, especially for peasants:
I believe pistols pistols are bad because you can not reliably down an enemy short range in one shot, while smg or small shotguns are great at it. Also at longer ranges you better fire a volley of fire with 0% to hit rather than a "precise" shot with average peasant accuracy, cause 0% to hit is actually like 5%. So I really like to use the Uzi-looking thing or small shotguns as sidearm/main weapon for peasants.
Best early SMG/Rifle?
Pretty much any rifle I have from loot, preferably harder hitting - If I have time and patience I will form a line with peasant not-so-snipers to shoot anything from out of visual range with World War I weapons. Any short to midrange situation is for sidearm shotguns/smgs/axes/dogs. I really hate UAC-carbines - it is like the lowest damage output option in the game.
Best early Throwable bomb?
I believe, for peasants there is no really good throwable option, because peasants are weak and clumsy - they can not throw far, precise or survive friendly fire. I would reccomend try bows or primed grenade personal delivery instead.
Black powder bombs are great early game, but they are not so great against an armored opponent. Molotovs are good for making them panick. I really love to make axe-centric compositions, so those two are my favourite skirmishing weapons early on, when my Gals can not get close and personal in one turn.