The target must be within range. There is normal range and long range for weapons.
You can attack a target with ½ or ¾ cover but not full cover.
Crossbows and the blowgun have the loading property. Your rate of fire is limited.
Magical ranged weapons and ammunition.
You can throw a bottle, frying pan, or a special item such as acid or alchemist's fire, as an improvised weapon.