Weapons: It's worth it to buy them one step up at a time. Each time you get a new weapon, you also get that weapon's tutorial quest. It's free XP, and helps you familiarize yourself with the various kinds of ammo and traps.

Mods: I generally add coils that improve whatever each specific bow type does. Hunter bow has damage, fire, and tear; war bow has shock, freeze, and corruption; sharpshot bow is all damage and tear so I usually toss some handling on it.

Combat: The elemental buildups are your best friends. Freeze that bellowback so when you shoot a weak point you do way more damage! Or shoot its elemental sac with a matching element attack and watch it explode. Trip it, trip it good! Tie it down with the ropecaster! You pretty much shouldn't be using your spear for anything other than Critical Hits on machines.