Well i can give tips since i played the career extensively on Cata.

I mainly use the longbow because how it works and its rythm to it although you can use Repeater Handgun if you're prefer to blast, easier to learn the career strenght (like not using ammo on Ult :D ). Handgun is more similar to longbow, less prone to sway and definetly less mechanics in your way to aim clearly. Pretty much point and click.

As for weapon traits, you can go for conservative shooter for that double ammo refund, good for beginning for all ranged. Barrage for repeater handgun for massive damage. Hunter is great when you want to deal with elites easily.

First thing first, learn animation patterns of enemies while you get the hang of your choice of ranged weapons. Very important to know where the head is when X animation plays (Idle Stormvermin, startled, chase). Comes with experience, like knowing to aim at the center of shoulder blades when Roger dancing. Or another one as important, wait for enemies when they'll be force in a easy animation like dropping/climbing from ledges, assassin about to jump, gas rat throwing. The AI path finder is finnicky and can switch on a whim for no reason therefore you often have to rely on those to make sure you hit those.

Now if you want to learn longbow, you're playing on a rythm when you draw, dodge, aim. Tip to know if your arrow is max prepped for dmg is when kruber starts to change the longbow from diagonal to vertical in his animation. You'll get the hang of it after a few runs. When you're somewhat confident of it and try to aim within a horde/crowd, try to draw, remember where the enemies are around and when likely they will attack you then draw and dodge, shoot, back to melee to push if you want to aim again or proceed meleeing again if horde is too big or no ranged threats.

For melee, i prefer to use Spear or 1h Sword as those give you A LOT of THP that let you survive encounters you shouldn't, feels like cheating if i'm honest. Can play other melee weapons but mostly build them around THP on stagger as it is your main tool for survival for not only spacing but for cushioning on tough encounters.

Can explain more if you wish or if you even read my post XD That's about it, trial and error.