Unfortunately this game is highly unforgiving and this is something ive been complaining about for ages.
Basically the best advice i can give you is to keep playing even if you keep failing until you figure out a meta that works.
Basically my advice to you is to focus on several things:
-early on focus on fighting humans, bandits to be precise, and focus on hunting down bandit thugs. Avoid fighting bandit raiders as they will wreck you early and into mid game (before you have a full party and leveled up brothers).
-experiment with meta and find out what works for you: i personally use 2 lines of 6 characters each; first line is shield + one handed weapon, where i focus on fatigue, melee and melee defense (so getting talents in that, melee def in particular is critical) with life and resolve being fillers in case i get low rolls on important stuff. For second i line i prefer to have characters that have about 60 melee and 60 ranged with the rest usually going into other things, such as life (they wont have shields, and arrows/bolts are deadly). The idea is that the first line tanks and second line shoots or switches to pikes and then stabs people from behind.
-spears are essentially a noob trap, and so are two handed axes; youre not supposed to be using that stuff (spears are fine very early game, axes only work if you have good melee skill, otherwise you wont hit anything, ever). Spears have very low damage and their special attack might appear good, but its not really, if you rely on it too much, it will fail you against tougher enemies (they will shield wall and simply drop into you). Early on when youre fighting unarmored enemies (bandit thugs) use swords; as you go up in skill and start getting 60+ melee guys i advise you to go into axes; i find axes to be the best all around weapons, specially for tanking characters. Aside from axes cleavers (military cleaver) seem to be pretty good too.
-bows vs crossbows – very high ranged skill bow can be deadly because you will essentially fire 2 times per turn, but bows will be utterly useless vs heavily armored enemies, such as orc warriors and skeletons, and up to couple of versions ago, vampires (they would brutalize ranged chars). Crossbows fire once per turn but can actually damaged armored opponents, with same problems as bows being there: undead are practically immune (except a few enemies) and vampires are a problem. So i suggest you focus on either one, but dont focus chars 100% of in. Hire people who have 50 in ranged with some talents, so that you can get it to 60 or 70, but at the same time develop the chars for melee, as you will need them to use 2 handed 2 range weapons when you fight big stuff (orc warriors!!!111). These guys also need higher life as they will stand there without a shield and catch enemy fire all the time.
Couple of notes for the end. This game offers a bunch of enemies that belong to different groups and are grouped in such a way that you need to know exactly what youre doing and toward what youre building your company. Some weapons (like ranged) might work brilliantly on bandits, which is early game, but you will need to go into mid or late game, and then face, for example, orc warriors which are practically immune to it (or skeletons). So you cant focus on one thing just because it works now and hope it will work forever because it wont. This is why i suggest that you build a frontline with high melee defense (shields + 1 handed weapon) capable of fighting anything (i prefer axes). And then a second line that can support them in different scenarios. I am still unable to build a company that can tackle everything, although i am pretty close now; the only thing that gives me headache now are undead with ghosts because you need exceptional resolve and some feats to be able to counter them (things you wont really need for 90% of the game otherwise).
So start small, make a crew that can farm bandits, start with thugs and then go into raiders; hoard money and items (raiders use ~110 armors and up to 140ish helmets, which are decent mid game entry gear) and start replacing your early members which will probably have bad stats and talents for those with expensive backgrounds (my favorites used to be raiders because they would get 50+ ranged and melee, meaning they would make perfect skirmisher that unloads 2 crossbow blots into your face before switching to melee).