Bows shoot with an arcing trajectory, which makes them very useful in dense terrain (but not in the forest, where the tree canopies are a major issue).
The Throwing skill commands both accuracy and a large part of bow damage, so don't expect good results from anyone with Throwing below 50; however, experienced soldiers can inflict fairly heavy damage using bows. High Stamina is also essential for an archer, since the larger bows put a major drain on it.
Bows don't get any accuracy bonus from kneeling, and shooting them costs a fixed amount of TUs, so make use of your mobility.
Arrows often inflict less damage to enemy Health than expected, so don't rely on them in 1 vs 1 situations.